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Mastitis (Clinical)

Mastitis is inflammation of the breast tissue with or without infection. The most common form of mastitis is associated with lactation in the first few weeks after birth. Non-lactational mastitis includes periductal mastitis and idiopathic granulomatous mastitis (IGM). Lactational mastitis is most commonly caused by Staphylococcus aureus that is introduced into the breast milk during breastfeeding. The etiology of non-lactational mastitis is poorly understood, but periductal mastitis is commonly associated with smoking, and IGM is frequently associated with Corynebacterium. Patients present with edema, erythema, tenderness, and, possibly, a mass in the breast. Diagnosis is usually clinical, although ultrasound, cultures, and biopsy may be required in some cases. Management involves antibiotics, analgesics, drainage of any abscesses, and surgical duct excision for periductal mastitis.

Last updated: Mar 4, 2024

Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

Overview

Definition

Mastitis Mastitis Mastitis is inflammation of the breast tissue with or without infection. The most common form of mastitis is associated with lactation in the first few weeks after birth. Non-lactational mastitis includes periductal mastitis and idiopathic granulomatous mastitis (IGM). Mastitis refers to inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation of the breast that may or may not be associated with infection.

Classification[3–5]

  • Lactational mastitis Lactational Mastitis Mastitis (most common)
  • Non-lactational mastitis Non-Lactational Mastitis Mastitis:
    • Periductal mastitis Periductal Mastitis Mastitis:
      • Inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation of subareolar breast ducts
      • Different from mammary ductal ectasia, which involves ductal dilation and primarily affects postmenopausal women
    • Idiopathic Idiopathic Dermatomyositis granulomatous mastitis Mastitis Mastitis is inflammation of the breast tissue with or without infection. The most common form of mastitis is associated with lactation in the first few weeks after birth. Non-lactational mastitis includes periductal mastitis and idiopathic granulomatous mastitis (IGM). Mastitis ( IGM IgM A class of immunoglobulin bearing mu chains (immunoglobulin mu-chains). Igm can fix complement. The name comes from its high molecular weight and originally being called a macroglobulin. Immunoglobulins: Types and Functions): peripheral inflammatory breast mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast

Epidemiology[1,2,4,5]

  • Lactational mastitis Lactational Mastitis Mastitis:
    • Affects up to 10% of breastfeeding Breastfeeding Breastfeeding is often the primary source of nutrition for the newborn. During pregnancy, hormonal stimulation causes the number and size of mammary glands in the breast to significantly increase. After delivery, prolactin stimulates milk production, while oxytocin stimulates milk expulsion through the lactiferous ducts, where it is sucked out through the nipple by the infant. Breastfeeding mothers
    • Most common in the first 3 months of lactation Lactation The processes of milk secretion by the maternal mammary glands after parturition. The proliferation of the mammary glandular tissue, milk synthesis, and milk expulsion or let down are regulated by the interactions of several hormones including estradiol; progesterone; prolactin; and oxytocin. Breastfeeding
  • Non-lactational mastitis Non-Lactational Mastitis Mastitis:
    • Periductal mastitis Periductal Mastitis Mastitis:
      • Most common in young women
      • Associated with smoking Smoking Willful or deliberate act of inhaling and exhaling smoke from burning substances or agents held by hand. Interstitial Lung Diseases
    • IGM IgM A class of immunoglobulin bearing mu chains (immunoglobulin mu-chains). Igm can fix complement. The name comes from its high molecular weight and originally being called a macroglobulin. Immunoglobulins: Types and Functions:
      • Rare
      • Most common in young, multiparous Multiparous A woman with prior deliveries Normal and Abnormal Labor women
      • Can occur in nulliparous women and men
      • In the United States, associated with Hispanic ethnicity

Etiology and Pathophysiology

Lactational mastitis Lactational Mastitis Mastitis[4,6,7]

  • Most commonly associated with staphylococcal infection
  • Poor milk drainage leads to milk stasis and growth of microorganisms.
  • Categories of inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation and infection in the lactating breast:[6]
    • Ductal narrowing: alveolar distension can lead to focal areas of congestion → edema Edema Edema is a condition in which excess serous fluid accumulates in the body cavity or interstitial space of connective tissues. Edema is a symptom observed in several medical conditions. It can be categorized into 2 types, namely, peripheral (in the extremities) and internal (in an organ or body cavity). Edema and erythema Erythema Redness of the skin produced by congestion of the capillaries. This condition may result from a variety of disease processes. Chalazion 
    • Galactocele Galactocele Benign Breast Conditions: a cyst-like collection of milk that occurs when milk outflow is obstructed due to ductal narrowing (no infection or erythema Erythema Redness of the skin produced by congestion of the capillaries. This condition may result from a variety of disease processes. Chalazion)
    • Inflammatory mastitis Mastitis Mastitis is inflammation of the breast tissue with or without infection. The most common form of mastitis is associated with lactation in the first few weeks after birth. Non-lactational mastitis includes periductal mastitis and idiopathic granulomatous mastitis (IGM). Mastitis: persistence of ductal narrowing can lead to inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation, with increasing erythema Erythema Redness of the skin produced by congestion of the capillaries. This condition may result from a variety of disease processes. Chalazion and edema Edema Edema is a condition in which excess serous fluid accumulates in the body cavity or interstitial space of connective tissues. Edema is a symptom observed in several medical conditions. It can be categorized into 2 types, namely, peripheral (in the extremities) and internal (in an organ or body cavity). Edema
    • Bacterial mastitis Mastitis Mastitis is inflammation of the breast tissue with or without infection. The most common form of mastitis is associated with lactation in the first few weeks after birth. Non-lactational mastitis includes periductal mastitis and idiopathic granulomatous mastitis (IGM). Mastitis: areas of inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation become infected with bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology
    • Phlegmons: fluid collections that occur in the setting of inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation, typically due to overly aggressive breast massage causing edema Edema Edema is a condition in which excess serous fluid accumulates in the body cavity or interstitial space of connective tissues. Edema is a symptom observed in several medical conditions. It can be categorized into 2 types, namely, peripheral (in the extremities) and internal (in an organ or body cavity). Edema and microvascular injury
    • Abscess Abscess Accumulation of purulent material in tissues, organs, or circumscribed spaces, usually associated with signs of infection. Chronic Granulomatous Disease: an infected fluid collection
  • Pathogens: 
    • Enter milk ducts during breastfeeding Breastfeeding Breastfeeding is often the primary source of nutrition for the newborn. During pregnancy, hormonal stimulation causes the number and size of mammary glands in the breast to significantly increase. After delivery, prolactin stimulates milk production, while oxytocin stimulates milk expulsion through the lactiferous ducts, where it is sucked out through the nipple by the infant. Breastfeeding (breast milk is not sterile Sterile Basic Procedures)
    • Usually come from mother’s skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions or infant’s mouth/ nose Nose The nose is the human body’s primary organ of smell and functions as part of the upper respiratory system. The nose may be best known for inhaling oxygen and exhaling carbon dioxide, but it also contributes to other important functions, such as tasting. The anatomy of the nose can be divided into the external nose and the nasal cavity. Nose Anatomy (External & Internal)
    • Most common infectious agents:
      • Staphylococcus aureus Staphylococcus aureus Potentially pathogenic bacteria found in nasal membranes, skin, hair follicles, and perineum of warm-blooded animals. They may cause a wide range of infections and intoxications. Brain Abscess (most common); may be methicillin-resistant S. aureus S. aureus Potentially pathogenic bacteria found in nasal membranes, skin, hair follicles, and perineum of warm-blooded animals. They may cause a wide range of infections and intoxications. Staphylococcus ( MRSA MRSA A strain of Staphylococcus aureus that is non-susceptible to the action of methicillin. The mechanism of resistance usually involves modification of normal or the presence of acquired penicillin binding proteins. Staphylococcus)
      • Group A or B Streptococcus Streptococcus Streptococcus is one of the two medically important genera of gram-positive cocci, the other being Staphylococcus. Streptococci are identified as different species on blood agar on the basis of their hemolytic pattern and sensitivity to optochin and bacitracin. There are many pathogenic species of streptococci, including S. pyogenes, S. agalactiae, S. pneumoniae, and the viridans streptococci. Streptococcus
      • Escherichia coli Escherichia coli The gram-negative bacterium Escherichia coli is a key component of the human gut microbiota. Most strains of E. coli are avirulent, but occasionally they escape the GI tract, infecting the urinary tract and other sites. Less common strains of E. coli are able to cause disease within the GI tract, most commonly presenting as abdominal pain and diarrhea. Escherichia coli
      • Corynebacterium Corynebacterium Corynebacteria are gram-positive, club-shaped bacilli. Corynebacteria are commonly isolated on tellurite or Loeffler’s media and have characteristic metachromatic granules. The major pathogenic species is Corynebacterium diphtheriae, which causes a severe respiratory infection called diphtheria. Corynebacterium
      • Bacteroides Bacteroides Bacteroides is a genus of opportunistic, anaerobic, gram-negative bacilli. Bacteroides fragilis is the most common species involved in human disease and is part of the normal flora of the large intestine. Bacteroides
  • Poor milk drainage or engorgement Engorgement Mastitis may result from:
    • Oversupply of milk
    • Infrequent feedings/pumping
    • Rapid weaning Weaning Techniques for effecting the transition of the respiratory-failure patient from mechanical ventilation to spontaneous ventilation, while meeting the criteria that tidal volume be above a given threshold (greater than 5 ml/kg), respiratory frequency be below a given count (less than 30 breaths/min), and oxygen partial pressure be above a given threshold (pao2 greater than 50mm hg). Weaning studies focus on finding methods to monitor and predict the outcome of mechanical ventilator weaning as well as finding ventilatory support techniques which will facilitate successful weaning. Present methods include intermittent mandatory ventilation, intermittent positive pressure ventilation, and mandatory minute volume ventilation. Invasive Mechanical Ventilation
    • Partial blockage of a duct
  • Additional risk factors:
    • Cracked nipples/ excoriation Excoriation Mastitis
    • Illness in the mother or baby
    • Mother’s stress and fatigue Fatigue The state of weariness following a period of exertion, mental or physical, characterized by a decreased capacity for work and reduced efficiency to respond to stimuli. Fibromyalgia
    • Depressed maternal immunity:
      • Human immunodeficiency Immunodeficiency Chédiak-Higashi Syndrome virus Virus Viruses are infectious, obligate intracellular parasites composed of a nucleic acid core surrounded by a protein capsid. Viruses can be either naked (non-enveloped) or enveloped. The classification of viruses is complex and based on many factors, including type and structure of the nucleoid and capsid, the presence of an envelope, the replication cycle, and the host range. Virology ( HIV HIV Anti-HIV Drugs)/acquired immunodeficiency Immunodeficiency Chédiak-Higashi Syndrome syndrome ( AIDS AIDS Chronic HIV infection and depletion of CD4 cells eventually results in acquired immunodeficiency syndrome (AIDS), which can be diagnosed by the presence of certain opportunistic diseases called AIDS-defining conditions. These conditions include a wide spectrum of bacterial, viral, fungal, and parasitic infections as well as several malignancies and generalized conditions. HIV Infection and AIDS)
      • Diabetes Diabetes Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of β cells in the pancreas and the resulting lack of insulin. Type 2 DM has a significant association with obesity and is characterized by insulin resistance. Diabetes Mellitus mellitus
      • Cancer

Non-lactational mastitis Non-Lactational Mastitis Mastitis[1,2,5,9]

Periductal mastitis Periductal Mastitis Mastitis:

  • Inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation of the subareolar ducts
  • Associated with smoking Smoking Willful or deliberate act of inhaling and exhaling smoke from burning substances or agents held by hand. Interstitial Lung Diseases
  • Exact etiology is unknown; possibilities include:
    • Smoking Smoking Willful or deliberate act of inhaling and exhaling smoke from burning substances or agents held by hand. Interstitial Lung Diseases, which damages subareolar ducts directly or through localized hypoxia Hypoxia Sub-optimal oxygen levels in the ambient air of living organisms. Ischemic Cell Damage
    • Squamous metaplasia Metaplasia A condition in which there is a change of one adult cell type to another similar adult cell type. Cellular Adaptation associated with mastitis Mastitis Mastitis is inflammation of the breast tissue with or without infection. The most common form of mastitis is associated with lactation in the first few weeks after birth. Non-lactational mastitis includes periductal mastitis and idiopathic granulomatous mastitis (IGM). Mastitis → partial duct blockage
    • Pathogenic organisms; isolated in 60%–85% of cases
    • Pathogens include:
      • Staphylococci (most common)
      • Enterococci
      • Bacteroides Bacteroides Bacteroides is a genus of opportunistic, anaerobic, gram-negative bacilli. Bacteroides fragilis is the most common species involved in human disease and is part of the normal flora of the large intestine. Bacteroides
      • Proteus Proteus Proteus spp. are gram-negative, facultatively anaerobic bacilli. Different types of infection result from Proteus, but the urinary tract is the most common site. The majority of cases are caused by Proteus mirabilis (P. mirabilis). The bacteria are part of the normal intestinal flora and are also found in the environment. Proteus

IGM IgM A class of immunoglobulin bearing mu chains (immunoglobulin mu-chains). Igm can fix complement. The name comes from its high molecular weight and originally being called a macroglobulin. Immunoglobulins: Types and Functions:

  • Peripheral inflammatory breast mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast
  • Usually unilateral
  • No association with breast cancer Breast cancer Breast cancer is a disease characterized by malignant transformation of the epithelial cells of the breast. Breast cancer is the most common form of cancer and 2nd most common cause of cancer-related death among women. Breast Cancer
  • Etiology is unknown.
  • Associated with Corynebacterium Corynebacterium Corynebacteria are gram-positive, club-shaped bacilli. Corynebacteria are commonly isolated on tellurite or Loeffler’s media and have characteristic metachromatic granules. The major pathogenic species is Corynebacterium diphtheriae, which causes a severe respiratory infection called diphtheria. Corynebacterium (although unclear if causative)

Clinical Presentation

General[3–5]

  • Mastitis Mastitis Mastitis is inflammation of the breast tissue with or without infection. The most common form of mastitis is associated with lactation in the first few weeks after birth. Non-lactational mastitis includes periductal mastitis and idiopathic granulomatous mastitis (IGM). Mastitis presents with edema Edema Edema is a condition in which excess serous fluid accumulates in the body cavity or interstitial space of connective tissues. Edema is a symptom observed in several medical conditions. It can be categorized into 2 types, namely, peripheral (in the extremities) and internal (in an organ or body cavity). Edema and erythema Erythema Redness of the skin produced by congestion of the capillaries. This condition may result from a variety of disease processes. Chalazion over the affected area. 
  • Abscesses may develop and present as tender, fluctuant Fluctuant Dermatologic Examination masses.

Lactational mastitis Lactational Mastitis Mastitis[4,7]

  • Edema Edema Edema is a condition in which excess serous fluid accumulates in the body cavity or interstitial space of connective tissues. Edema is a symptom observed in several medical conditions. It can be categorized into 2 types, namely, peripheral (in the extremities) and internal (in an organ or body cavity). Edema, erythema Erythema Redness of the skin produced by congestion of the capillaries. This condition may result from a variety of disease processes. Chalazion, and warmth
  • Usually unilateral
  • Systemic symptoms of infection:
    • Fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever/ chills Chills The sudden sensation of being cold. It may be accompanied by shivering. Fever
    • Fatigue Fatigue The state of weariness following a period of exertion, mental or physical, characterized by a decreased capacity for work and reduced efficiency to respond to stimuli. Fibromyalgia/general malaise Malaise Tick-borne Encephalitis Virus
    • Myalgias Myalgias Painful sensation in the muscles. Tick-borne Encephalitis Virus (muscle aches) 
  • Pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways during breastfeeding Breastfeeding Breastfeeding is often the primary source of nutrition for the newborn. During pregnancy, hormonal stimulation causes the number and size of mammary glands in the breast to significantly increase. After delivery, prolactin stimulates milk production, while oxytocin stimulates milk expulsion through the lactiferous ducts, where it is sucked out through the nipple by the infant. Breastfeeding
  • Regional lymphadenopathy Lymphadenopathy Lymphadenopathy is lymph node enlargement (> 1 cm) and is benign and self-limited in most patients. Etiologies include malignancy, infection, and autoimmune disorders, as well as iatrogenic causes such as the use of certain medications. Generalized lymphadenopathy often indicates underlying systemic disease. Lymphadenopathy (tender and enlarged lymph nodes Lymph Nodes They are oval or bean shaped bodies (1 – 30 mm in diameter) located along the lymphatic system. Lymphatic Drainage System: Anatomy)
  • Fluctuant Fluctuant Dermatologic Examination, tender mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast ( abscess Abscess Accumulation of purulent material in tissues, organs, or circumscribed spaces, usually associated with signs of infection. Chronic Granulomatous Disease in 3%–11% of cases)
Lactational mastitis

Lactational mastitis presents as an edematous and erythematous breast.

Image: “atlasofclinicals00bock” by Internet Archive Book Images. License: Public Domain

Periductal mastitis Periductal Mastitis Mastitis[2,5,9]

  • Periareolar inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation
  • Nipple Nipple The conic organs which usually give outlet to milk from the mammary glands. Examination of the Breast discharge
  • Fluctuant Fluctuant Dermatologic Examination, tender mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast ( abscess Abscess Accumulation of purulent material in tissues, organs, or circumscribed spaces, usually associated with signs of infection. Chronic Granulomatous Disease); can rupture and drain at the edge of areola Areola Examination of the Breast
  • Draining cutaneous fistula Fistula Abnormal communication most commonly seen between two internal organs, or between an internal organ and the surface of the body. Anal Fistula (from chronic/recurrent abscess Abscess Accumulation of purulent material in tissues, organs, or circumscribed spaces, usually associated with signs of infection. Chronic Granulomatous Disease)

IGM IgM A class of immunoglobulin bearing mu chains (immunoglobulin mu-chains). Igm can fix complement. The name comes from its high molecular weight and originally being called a macroglobulin. Immunoglobulins: Types and Functions[1,5]

  • Peripheral inflammatory breast mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast
  • May also develop:
    • Multiple areas of peripheral infection
    • Multiple small abscesses
    • Overlying skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions ulcers 
  • Often mimics breast cancer Breast cancer Breast cancer is a disease characterized by malignant transformation of the epithelial cells of the breast. Breast cancer is the most common form of cancer and 2nd most common cause of cancer-related death among women. Breast Cancer:
Igm of the right breast

Idiopathic granulomatous mastitis (status post-incisional breast biopsy)

Image: “IGM of the right breast” by Dept. of Radiation Oncology, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA. License: CC BY 2.0

Diagnosis

Lactating mothers[6,7]

  • Diagnosis is established based on clinical presentation.
  • Supportive studies:
    • Gram stain Gram stain Klebsiella and culture of the milk:
      • Can help identify the causative organisms 
      • Only required in cases refractory to treatment
    • Blood culture: for severe progressive infection/signs of sepsis Sepsis Systemic inflammatory response syndrome with a proven or suspected infectious etiology. When sepsis is associated with organ dysfunction distant from the site of infection, it is called severe sepsis. When sepsis is accompanied by hypotension despite adequate fluid infusion, it is called septic shock. Sepsis and Septic Shock
    • Ultrasound:
      • To look for abscess Abscess Accumulation of purulent material in tissues, organs, or circumscribed spaces, usually associated with signs of infection. Chronic Granulomatous Disease → appears as a fluid-filled mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast
      • If a mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast is present on exam 
      • If there is no clinical improvement after 48–72 hours of empiric antibiotics
Abscess on ultrasound in diagnosis of mastitis

Ultrasound imaging of a breast abscess:
A: complex, with ill-defined borders
B: homogeneous in appearance with well-defined borders

Image: “Abscess” by Antônio Arildo Reginaldo de Holanda et al. License: CC BY 4.0

Non-lactating women[1,9]

Periductal mastitis Periductal Mastitis Mastitis:

  • Diagnosis is based on clinical presentation.
  • Ultrasound can be obtained to rule out abscess Abscess Accumulation of purulent material in tissues, organs, or circumscribed spaces, usually associated with signs of infection. Chronic Granulomatous Disease.

IGM IgM A class of immunoglobulin bearing mu chains (immunoglobulin mu-chains). Igm can fix complement. The name comes from its high molecular weight and originally being called a macroglobulin. Immunoglobulins: Types and Functions:

  • Clinical presentation: may mimic breast cancer Breast cancer Breast cancer is a disease characterized by malignant transformation of the epithelial cells of the breast. Breast cancer is the most common form of cancer and 2nd most common cause of cancer-related death among women. Breast Cancer
  • Laboratory studies:
    • Gram stain Gram stain Klebsiella and culture of any nipple Nipple The conic organs which usually give outlet to milk from the mammary glands. Examination of the Breast discharge
    • Prolactin Prolactin A lactogenic hormone secreted by the adenohypophysis. It is a polypeptide of approximately 23 kd. Besides its major action on lactation, in some species prolactin exerts effects on reproduction, maternal behavior, fat metabolism, immunomodulation and osmoregulation. Breasts: Anatomy: may be ↑ in IGM IgM A class of immunoglobulin bearing mu chains (immunoglobulin mu-chains). Igm can fix complement. The name comes from its high molecular weight and originally being called a macroglobulin. Immunoglobulins: Types and Functions 
  • Imaging:
  • Core needle biopsy Core Needle Biopsy Fibrocystic Change (CNB):
    • Biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma suspicious masses found on ultrasound
    • Send for gram stain Gram stain Klebsiella, culture, and histopathology.
    • IGM IgM A class of immunoglobulin bearing mu chains (immunoglobulin mu-chains). Igm can fix complement. The name comes from its high molecular weight and originally being called a macroglobulin. Immunoglobulins: Types and Functions findings:
      • Non-caseating, non-necrotizing granulomatous inflammation Granulomatous Inflammation Chalazion
      • Negative for acid-fast bacilli Acid-fast bacilli Mycobacterium or fungi Fungi A kingdom of eukaryotic, heterotrophic organisms that live parasitically as saprobes, including mushrooms; yeasts; smuts, molds, etc. They reproduce either sexually or asexually, and have life cycles that range from simple to complex. Filamentous fungi, commonly known as molds, refer to those that grow as multicellular colonies. Mycology
      • Cultures may grow Corynebacterium Corynebacterium Corynebacteria are gram-positive, club-shaped bacilli. Corynebacteria are commonly isolated on tellurite or Loeffler’s media and have characteristic metachromatic granules. The major pathogenic species is Corynebacterium diphtheriae, which causes a severe respiratory infection called diphtheria. Corynebacterium.

Management

Lactational mastitis Lactational Mastitis Mastitis

  • Supportive care:[6]
    • Reassurance Reassurance Clinician–Patient Relationship and education on normal lactation Lactation The processes of milk secretion by the maternal mammary glands after parturition. The proliferation of the mammary glandular tissue, milk synthesis, and milk expulsion or let down are regulated by the interactions of several hormones including estradiol; progesterone; prolactin; and oxytocin. Breastfeeding physiology
    • Analgesics ( nonsteroidal antiinflammatory drugs Nonsteroidal Antiinflammatory Drugs Nonsteroidal antiinflammatory drugs (NSAIDs) are a class of medications consisting of aspirin, reversible NSAIDs, and selective NSAIDs. NSAIDs are used as antiplatelet, analgesic, antipyretic, and antiinflammatory agents. Nonsteroidal Antiinflammatory Drugs (NSAIDs), acetaminophen Acetaminophen Acetaminophen is an over-the-counter nonopioid analgesic and antipyretic medication and the most commonly used analgesic worldwide. Despite the widespread use of acetaminophen, its mechanism of action is not entirely understood. Acetaminophen)
    • Cold compresses
    • Wear a supportive bra.
    • Frequent, complete emptying of breast via:
      • Breastfeeding Breastfeeding Breastfeeding is often the primary source of nutrition for the newborn. During pregnancy, hormonal stimulation causes the number and size of mammary glands in the breast to significantly increase. After delivery, prolactin stimulates milk production, while oxytocin stimulates milk expulsion through the lactiferous ducts, where it is sucked out through the nipple by the infant. Breastfeeding
      • Pumping
      • Hand Hand The hand constitutes the distal part of the upper limb and provides the fine, precise movements needed in activities of daily living. It consists of 5 metacarpal bones and 14 phalanges, as well as numerous muscles innervated by the median and ulnar nerves. Hand: Anatomy expression
    • However, do not continuously “ pump Pump ACES and RUSH: Resuscitation Ultrasound Protocols until empty,” as it can perpetuate a cycle of hyperlactation, which worsens inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation and edema Edema Edema is a condition in which excess serous fluid accumulates in the body cavity or interstitial space of connective tissues. Edema is a symptom observed in several medical conditions. It can be categorized into 2 types, namely, peripheral (in the extremities) and internal (in an organ or body cavity). Edema.
  • Antibiotics:
    • Should be reserved for bacterial (rather than simply inflammatory) mastitis Mastitis Mastitis is inflammation of the breast tissue with or without infection. The most common form of mastitis is associated with lactation in the first few weeks after birth. Non-lactational mastitis includes periductal mastitis and idiopathic granulomatous mastitis (IGM). Mastitis[6]
    • Direct breastfeeding Breastfeeding Breastfeeding is often the primary source of nutrition for the newborn. During pregnancy, hormonal stimulation causes the number and size of mammary glands in the breast to significantly increase. After delivery, prolactin stimulates milk production, while oxytocin stimulates milk expulsion through the lactiferous ducts, where it is sucked out through the nipple by the infant. Breastfeeding should continue during antibiotic therapy[6]
    • Non-MRSA:
      • Antistaphylococcal penicillins Antistaphylococcal Penicillins Penicillins: dicloxacillin Dicloxacillin One of the penicillins which is resistant to penicillinase. Penicillins 500 mg by mouth 4 times daily[6,8]
      • Cephalosporins Cephalosporins Cephalosporins are a group of bactericidal beta-lactam antibiotics (similar to penicillins) that exert their effects by preventing bacteria from producing their cell walls, ultimately leading to cell death. Cephalosporins are categorized by generation and all drug names begin with “cef-” or “ceph-.” Cephalosporins: cephalexin 500 mg by mouth 4 times daily[6,8]
      • Erythromycin Erythromycin A bacteriostatic antibiotic macrolide produced by streptomyces erythreus. Erythromycin a is considered its major active component. In sensitive organisms, it inhibits protein synthesis by binding to 50s ribosomal subunits. This binding process inhibits peptidyl transferase activity and interferes with translocation of amino acids during translation and assembly of proteins. Macrolides and Ketolides ( beta-lactam Beta-Lactam Penicillins hypersensitivity) 250 mg by mouth 4 times daily[8] OR 500 mg by mouth twice daily[5]
    • MRSA MRSA A strain of Staphylococcus aureus that is non-susceptible to the action of methicillin. The mechanism of resistance usually involves modification of normal or the presence of acquired penicillin binding proteins. Staphylococcus:
      • Clindamycin Clindamycin An antibacterial agent that is a semisynthetic analog of lincomycin. Lincosamides 300‒450 mg by mouth 4 times daily (higher risk of Clostridium difficile Clostridium difficile A common inhabitant of the colon flora in human infants and sometimes in adults. The type species clostridioides difficile is formerly known as Clostridium difficile. It is a causative agent for clostridioides infections and is associated with pseudomembranous enterocolitis in patients receiving antibiotic therapy. Clostridia colitis Colitis Inflammation of the colon section of the large intestine, usually with symptoms such as diarrhea (often with blood and mucus), abdominal pain, and fever. Pseudomembranous Colitis)[6,8]
      • Trimethoprim Trimethoprim The sulfonamides are a class of antimicrobial drugs inhibiting folic acid synthesize in pathogens. The prototypical drug in the class is sulfamethoxazole. Although not technically sulfonamides, trimethoprim, dapsone, and pyrimethamine are also important antimicrobial agents inhibiting folic acid synthesis. The agents are often combined with sulfonamides, resulting in a synergistic effect. Sulfonamides and Trimethoprim sulfamethoxazole Sulfamethoxazole A bacteriostatic antibacterial agent that interferes with folic acid synthesis in susceptible bacteria. Its broad spectrum of activity has been limited by the development of resistance. Sulfonamides and Trimethoprim (avoid in mothers who are breastfeeding Breastfeeding Breastfeeding is often the primary source of nutrition for the newborn. During pregnancy, hormonal stimulation causes the number and size of mammary glands in the breast to significantly increase. After delivery, prolactin stimulates milk production, while oxytocin stimulates milk expulsion through the lactiferous ducts, where it is sucked out through the nipple by the infant. Breastfeeding infants < 1 month old owing to risk of hyperbilirubinemia Hyperbilirubinemia A condition characterized by an abnormal increase of bilirubin in the blood, which may result in jaundice. Bilirubin, a breakdown product of heme, is normally excreted in the bile or further catabolized before excretion in the urine. Jaundice) 160/800 mg by mouth twice daily[6,8]
      • IV vancomycin Vancomycin Antibacterial obtained from streptomyces orientalis. It is a glycopeptide related to ristocetin that inhibits bacterial cell wall assembly and is toxic to kidneys and the inner ear. Glycopeptides may be required for severe/septic presentation 30 mg/kg loading dose Loading Dose Dosage Calculation, then 15 mg/kg IV twice daily.[8]
    • Duration: unclear
      • May be anywhere from 5–14 days[5]
      • Longer courses (10–14 days) reduce risk of relapse Relapse Relapsing Fever and are recommended by the (international) Academy of Breastfeeding Breastfeeding Breastfeeding is often the primary source of nutrition for the newborn. During pregnancy, hormonal stimulation causes the number and size of mammary glands in the breast to significantly increase. After delivery, prolactin stimulates milk production, while oxytocin stimulates milk expulsion through the lactiferous ducts, where it is sucked out through the nipple by the infant. Breastfeeding Medicine[6]
      • Shorter courses may be effective if there is a rapid and complete response.
  • Surgical therapy: incision and drainage Incision And Drainage Chalazion of associated abscesses

Non-lactational mastitis Non-Lactational Mastitis Mastitis

Periductal mastitis Periductal Mastitis Mastitis:

  • Often a chronic problem
  • Antibiotics:[5]
    • Amoxicillin-clavulanate (1st line) 875 mg by mouth twice daily
    • Trimethoprim Trimethoprim The sulfonamides are a class of antimicrobial drugs inhibiting folic acid synthesize in pathogens. The prototypical drug in the class is sulfamethoxazole. Although not technically sulfonamides, trimethoprim, dapsone, and pyrimethamine are also important antimicrobial agents inhibiting folic acid synthesis. The agents are often combined with sulfonamides, resulting in a synergistic effect. Sulfonamides and Trimethoprim sulfamethoxazole Sulfamethoxazole A bacteriostatic antibacterial agent that interferes with folic acid synthesis in susceptible bacteria. Its broad spectrum of activity has been limited by the development of resistance. Sulfonamides and Trimethoprim 160/800 mg by mouth twice daily or doxycycline 100 mg twice daily if there is a concern for MRSA MRSA A strain of Staphylococcus aureus that is non-susceptible to the action of methicillin. The mechanism of resistance usually involves modification of normal or the presence of acquired penicillin binding proteins. Staphylococcus
    • Duration of treatment usually 5–7 days
    • High risk of recurrence with antibiotics alone[9]
  • Abscess Abscess Accumulation of purulent material in tissues, organs, or circumscribed spaces, usually associated with signs of infection. Chronic Granulomatous Disease:
  • Fistulas and recurrent abscesses:
    • Surgical excision of involved ducts
    • Open or excise fistulous tract
    • Because fistulas and abscesses are present in the majority of cases, surgical treatment is a mainstay of therapy to minimize the risk of recurrence.[9]
  • Smoking Smoking Willful or deliberate act of inhaling and exhaling smoke from burning substances or agents held by hand. Interstitial Lung Diseases cessation: associated with decreased risk of recurrence[5]

IGM IgM A class of immunoglobulin bearing mu chains (immunoglobulin mu-chains). Igm can fix complement. The name comes from its high molecular weight and originally being called a macroglobulin. Immunoglobulins: Types and Functions:

  • Usually self-limiting Self-Limiting Meningitis in Children and will resolve, but may take up to 20 months
  • Secondary infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease treated with antibiotics and drainage of abscesses if necessary:
    • Empirically can be given same antibiotics as periductal mastitis Periductal Mastitis Mastitis
    • Adjust antibiotics based on culture and susceptibility.
    • Doxycycline 100 mg by mouth twice daily for Corynebacterium Corynebacterium Corynebacteria are gram-positive, club-shaped bacilli. Corynebacteria are commonly isolated on tellurite or Loeffler’s media and have characteristic metachromatic granules. The major pathogenic species is Corynebacterium diphtheriae, which causes a severe respiratory infection called diphtheria. Corynebacterium[5] 
    • Typical course is 5–7 days (if responsive to treatment), but may be extended to 2 weeks if needed.
  • Persistent and refractory IGM IgM A class of immunoglobulin bearing mu chains (immunoglobulin mu-chains). Igm can fix complement. The name comes from its high molecular weight and originally being called a macroglobulin. Immunoglobulins: Types and Functions: Steroids Steroids A group of polycyclic compounds closely related biochemically to terpenes. They include cholesterol, numerous hormones, precursors of certain vitamins, bile acids, alcohols (sterols), and certain natural drugs and poisons. Steroids have a common nucleus, a fused, reduced 17-carbon atom ring system, cyclopentanoperhydrophenanthrene. Most steroids also have two methyl groups and an aliphatic side-chain attached to the nucleus. Benign Liver Tumors and methotrexate Methotrexate An antineoplastic antimetabolite with immunosuppressant properties. It is an inhibitor of tetrahydrofolate dehydrogenase and prevents the formation of tetrahydrofolate, necessary for synthesis of thymidylate, an essential component of DNA. Antimetabolite Chemotherapy can be used.
  • Surgery is typically not recommended in IGM IgM A class of immunoglobulin bearing mu chains (immunoglobulin mu-chains). Igm can fix complement. The name comes from its high molecular weight and originally being called a macroglobulin. Immunoglobulins: Types and Functions.[5]

Differential Diagnosis

  • Inflammatory breast cancer Breast cancer Breast cancer is a disease characterized by malignant transformation of the epithelial cells of the breast. Breast cancer is the most common form of cancer and 2nd most common cause of cancer-related death among women. Breast Cancer: a rare, aggressive, rapidly growing breast cancer Breast cancer Breast cancer is a disease characterized by malignant transformation of the epithelial cells of the breast. Breast cancer is the most common form of cancer and 2nd most common cause of cancer-related death among women. Breast Cancer characterized by erythema Erythema Redness of the skin produced by congestion of the capillaries. This condition may result from a variety of disease processes. Chalazion and edema Edema Edema is a condition in which excess serous fluid accumulates in the body cavity or interstitial space of connective tissues. Edema is a symptom observed in several medical conditions. It can be categorized into 2 types, namely, peripheral (in the extremities) and internal (in an organ or body cavity). Edema. Almost all women have lymph Lymph The interstitial fluid that is in the lymphatic system. Secondary Lymphatic Organs node involvement and up to ⅓ of women will have distant metastases upon presentation. The diagnosis should be suspected in women with rapidly progressive inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation without improvement after antibiotics. Breast imaging Breast Imaging Female breasts, made of glandular, adipose, and connective tissue, are hormone-sensitive organs that undergo changes along with the menstrual cycle and during pregnancy. Breasts may be affected by various diseases, in which different imaging methods are important to arrive at the correct diagnosis and management. Mammography is used for breast cancer screening and diagnostic evaluation of various breast-related symptoms. Imaging of the Breast with a diagnostic mammogram Mammogram Fibrocystic Change and ultrasound along with a CNB can confirm the diagnosis. Treatment involves surgery, chemotherapy Chemotherapy Osteosarcoma, and radiation Radiation Emission or propagation of acoustic waves (sound), electromagnetic energy waves (such as light; radio waves; gamma rays; or x-rays), or a stream of subatomic particles (such as electrons; neutrons; protons; or alpha particles). Osteosarcoma.
  • Breast abscess Breast Abscess Benign Breast Conditions: the accumulation of pus within the mammary gland Mammary gland Glandular tissue in the breast of human that is under the influence of hormones such as estrogens; progestins; and prolactin. In women, after parturition, the mammary glands secrete milk for the nourishment of the young. Breasts: Anatomy that is usually associated with mastitis Mastitis Mastitis is inflammation of the breast tissue with or without infection. The most common form of mastitis is associated with lactation in the first few weeks after birth. Non-lactational mastitis includes periductal mastitis and idiopathic granulomatous mastitis (IGM). Mastitis. Presents as a unilateral and fluctuant Fluctuant Dermatologic Examination mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast within a painful, erythematous, and edematous breast. Treatment involves incision and drainage Incision And Drainage Chalazion.
  • Galactocele Galactocele Benign Breast Conditionsa cystic Cystic Fibrocystic Change collection of fluid usually caused by an obstructed milk duct. Galactoceles present as a palpable, firm mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast in the subareolar region and may show a classic fat-fluid level Fat-Fluid Level Imaging of the Mediastinum on imaging. Unlike lactational mastitis Lactational Mastitis Mastitis, galactoceles are not associated with systemic symptoms such as fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, malaise Malaise Tick-borne Encephalitis Virus, or myalgias Myalgias Painful sensation in the muscles. Tick-borne Encephalitis Virus. Diagnosis is based on history and aspiration, yielding milky fluid. These lesions do not require excision.
  • Mammary duct ectasia Mammary Duct Ectasia Examination of the Breast: dilation of the subareolar ducts associated with fibrosis Fibrosis Any pathological condition where fibrous connective tissue invades any organ, usually as a consequence of inflammation or other injury. Bronchiolitis Obliterans and thick, creamy nipple Nipple The conic organs which usually give outlet to milk from the mammary glands. Examination of the Breast discharge. Previously considered part of the same syndrome as periductal mastitis Periductal Mastitis Mastitis, mammary duct ectasia Mammary Duct Ectasia Examination of the Breast is now considered to be an age-related phenomenon that is not associated with significant inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation or infection. Ectasia typically occurs in postmenopausal women, while periductal mastitis Periductal Mastitis Mastitis usually occurs in younger women, especially those who smoke.

References

  1. Al-Khaffaf B, Knox F, Bundred NJ. (2008). Idiopathic granulomatous mastitis: a 25-year experience. J Am Coll Surg 206(2):269. https://pubmed.ncbi.nlm.nih.gov/18222379/
  2. Ammari FF, Yaghan RJ, Omari AK. (2002). Periductal mastitis: clinical characteristics and outcome. Saudi Med J 23(7):819. https://pubmed.ncbi.nlm.nih.gov/12174233/
  3. Beckmann CRB, Ling FW, et al. (Eds.). Obstetrics and gynecology, 6th ed., p. 127.
  4. Dixon JM. (2020). Lactational mastitis. UpToDate. Retrieved February 1, 2021, from https://www.uptodate.com/contents/lactational-mastitis
  5. Dixon JM, Pariser KM. (2020). Nonlactational mastitis in adults. UpToDate. Retrieved February 1, 2021, from https://www.uptodate.com/contents/nonlactational-mastitis-in-adults
  6. Mitchell KB, Johnson HM, Rodriguez JM, et. al. (2022). Academy of Breastfeeding Medicine clinical protocol #36: the mastitis spectrum, revised 2022. Breastfeeding Medicine, 17(5):2022. doi: 10.1089/bfm.2022.29207.kbm https://pubmed.ncbi.nlm.nih.gov/35576513/
  7. Schoenfeld EM, McKay MP. (2010). Mastitis and methicillin-resistant Staphylococcus aureus (MRSA): the calm before the storm? J Emerg Med, 38(4):e31. Epub 2009 Feb 20. https://pubmed.ncbi.nlm.nih.gov/19232875/
  8. Stevens DL Bisno AL, Chambers HF, et al. (2014). Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America. Clin Infect Dis, 59(2):e10–e52. https://doi.org/10.1093/cid/ciu296.
  9. Zhang Y, Zhou Y, Mao F, Guan J, Sun Q. (2018). Clinical characteristics, classification and surgical treatment of periductal mastitis. J Thorac Dis, 10(4):2420–2427. doi: 10.21037/jtd.2018.04.22 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5949503/

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