Dermatopatología (ENARM / Atención médica al paciente)

Pityriasis rosea is an acute, self-limited skin disease. The etiology is not known, and it commonly occurs in young adults. Patients initially present with a single, ovoid “herald patch.” This is followed by diffuse, pruritic, scaly, oval lesions over the trunk (often in a “Christmas tree” distribution on the back) and extremities. The diagnosis is clinical. Pityriasis rosea is a self-limiting condition; therefore, usually no treatment is required. However, topical steroids and antihistamines may be used for pruritus, if needed.

Impetigo is a highly contagious superficial bacterial infection typically caused by Staphylococcus aureus (most common) and Streptococcus pyogenes. Impetigo most commonly presents in children aged 2 to 5 years with lesions that evolve from papules to vesicles to pustules, which eventually break down to form characteristic “honey-colored” crusts. Infection can either be primary (bacterial infection of healthy, intact skin) or secondary (infection of pre-existing abrasions). The diagnosis is clinical, and management includes topical or systemic antibiotic therapy. Complications of impetigo include post-streptococcal glomerulonephritis, cellulitis, and scarlet fever.

Diabetes mellitus (DM) is a chronic metabolic disorder characterized by persistent hyperglycemia due to impaired insulin secretion (type 1 DM), insulin resistance (type 2 DM), or both (latent autoimmune diabetes in adults (LADA)). The goal of diabetes management is to prevent chronic serious and potentially disabling complications due to damage to various organs. Adequate long-term control of blood glucose is crucial in the prevention of complications. Macrovascular complications include heart disease, stroke, peripheral vascular disease, and CKD in various stages, including end-stage renal disease that requires dialysis. Microvascular disease can cause retinopathy, neuropathy, or symptomatic cardiac disease, which are not seen during stress testing or angiogram that are used to diagnose large vessel diseases.

Candida is a genus of dimorphic, opportunistic fungi. Candida albicans is part of the normal human flora and is the most common cause of candidiasis. Risk factors for infection include conditions or agents that may lead to an immunocompromised state, disruption of the normal flora, and/or disturbance of the mucosal barrier. The clinical presentation varies and can include localized mucocutaneous infections (e.g., oropharyngeal, esophageal, intertriginous, and vulvovaginal candidiasis) and invasive disease (e.g., candidemia, intraabdominal abscess, pericarditis, and meningitis). The diagnosis is made by identifying Candida on KOH preparation, cultures, or tissue biopsy. Treatment depends on the extent and site of infection, and includes topical or systemic antifungal medications

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. The skin is composed of surface epithelium, exocrine components, connective tissue, muscles, and nerves. The primary role of the skin is to serve as a protective barrier between the internal body and the external environment; it also protects the body from excessive fluid loss.

Seborrheic dermatitis is a common chronic, relapsing skin disorder that presents as erythematous plaques with greasy, yellow scales in susceptible areas (scalp, face, and trunk). Seborrheic dermatitis has a biphasic incidence, occurring in two peaks: first in infants, then in adolescence and early adulthood. Although the exact etiology is unknown, pathologic mechanisms have been observed involving the sebaceous glands and Malassezia on the skin. Topical medications are used for acute exacerbation or maintenance treatment. These options aim to inhibit skin colonization (antifungal agents), reduce inflammation (steroids, calcineurin inhibitors), and loosen scales and crusts (keratolytic agents). Severe and refractory seborrheic dermatitis may warrant the use of systemic antifungal medications.

Psoriasis is a common T-cell–mediated inflammatory skin condition. The etiology is unknown, but is thought to be due to genetic inheritance and environmental triggers. There are 4 major subtypes, with the most common form being chronic plaque psoriasis. Plaques are well-circumscribed and salmon-colored, with silvery scales. Plaques commonly appear on the scalp and extensor surfaces of the extremities. Diagnosis is clinical. Treatment options are determined by the percentage of body surface area (BSA) affected and include topical corticosteroids, retinoids, calcineurin inhibitors, disease-modifying antirheumatic drugs (DMARDs), biologics, and phototherapy.

Rosacea is a chronic inflammatory disease of the skin that is associated with capillary hyperreactivity. This condition is predominantly seen in middle-aged women, and is more common in fair-skinned patients. Patients may have facial erythema, flushing, telangiectasia, papules, pustules, phymatous changes, and ocular manifestations. The diagnosis is clinical. Management includes avoidance of triggers, gentle skincare, topical (and/or oral) antibiotics, and laser (or surgical) therapies.

Acne vulgaris, also known as acne, is a common disorder of the pilosebaceous units in adolescents and young adults. The condition occurs due to follicular hyperkeratinization, excess sebum production, follicular colonization by Cutibacterium acnes, and inflammation. Acne can present as open or closed comedones, papules, pustules, nodules, or cysts. The diagnosis is based on clinical exam. Management depends on the severity, but includes skin care techniques, topical therapies, antibiotics, and retinoids.

Seborrheic keratosis (SK) is the most common benign epithelial cutaneous neoplasm. The condition consists of immature keratinocytes. Seborrheic keratosis is the most common benign skin tumor in middle-aged and elderly adults and presents as a sharply demarcated, exophytic, skin lesion that may be tan or black and has a “stuck-on” appearance. Pruritus or pain can occur if these lesions become secondarily inflamed by trauma, especially if they are within the skin folds. Genetics are thought to play a role, but the pathogenesis is uncertain. The most common mutations involve two oncogenes: fibroblast growth factor receptor 3 (FGFR3) and PIK3CA. There is a familial predisposition to develop a high number of seborrheic keratoses. Treatment is not necessary, as this is a benign condition, but cryotherapy, curettage or electrodesiccation can be performed for discomfort or cosmetic concerns.

The identification and classification of skin lesions in a patient are important steps in the diagnosis of any skin disorder. Primary lesions represent the initial presentation of the disease process. Secondary lesions develop from irritated or manipulated primary lesions, and/or disease progression. Along with history, a comprehensive examination of the skin, appendages, and mucous membranes is required to differentiate between conditions. The key features noted during examination include the type, morphology, size, color, shape, arrangement, and distribution of the presenting lesions. At times, diagnostic procedures may be necessary.

Malassezia is a lipophilic yeast commonly found on the skin surfaces of many animals, including humans. In the presence of certain environments or triggers, this fungus can cause pathologic diseases ranging from superficial skin conditions (tinea versicolor and dermatitis) to invasive disease (e.g., Malassezia folliculitis, catheter-associated fungemia, meningitis, and urinary tract infections). Patients with tinea versicolor develop an asymptomatic or mildly pruritic hypopigmented or hyperpigmented rash on the chest, back, abdomen, or face. Seborrheic dermatitis presents with an erythematous, pruritic rash with greasy scales and yellow crust, most commonly affecting areas of the face, upper trunk, or intertriginous regions. The presentation of Malassezia folliculitis is similar to that of bacterial folliculitis, with pruritic, monomorphic papules or pustules in a follicular pattern. The diagnosis of the superficial skin conditions is primarily by exam, but may be confirmed by microscopy of skin scrapings. Management entails the use of topical and oral antifungal agents.

Herpes zoster (also known as shingles) is a viral, reactivation infection caused by the varicella-zoster virus (VZV). Latent VZV remains dormant in the dorsal root ganglion after the primary infection phase of varicella (chickenpox). Age, stress, or immunocompromised states can trigger the reactivation of the virus. Herpes zoster clinically presents in a single, dermatomal distribution as a painful, unilateral rash. The diagnosis is primarily made from the history and physical examination. However, laboratory testing (such as PCR) can be performed if the diagnosis is unclear. Management includes antiviral therapy and symptomatic treatment.

Human papillomavirus (HPV) is a nonenveloped, circular, double-stranded DNA virus belonging to the Papillomaviridae family. Humans are the only reservoir, and transmission occurs through close skin-to-skin or sexual contact. Human papillomaviruses infect basal epithelial cells and can affect cell-regulatory proteins to result in cell proliferation. There are > 200 serotypes that can cause several conditions, including cutaneous warts, anogenital warts, and neoplasms.

Porphyrias are a group of metabolic disorders caused by a disturbance in the synthesis of heme. In most cases, porphyria is caused by a hereditary enzyme defect. The disease patterns differ depending on the affected enzyme, and the variants of porphyria can be clinically differentiated between acute and nonacute forms. Patients with porphyria present with photosensitive skin eruptions and sometimes systemic symptoms such as abdominal pain and neuropathy. Porphyrias are managed by avoiding triggers, such as sun exposure and consumption of alcohol. When flares occur, therapy is targeted toward symptomatic relief.

Ichthyosis vulgaris is the most common type of keratinization disorders. The condition occurs due to an autosomal dominant mutation in the filaggrin gene, which results in skin-barrier dysfunction. Patients present in early childhood with rough, dry, and scaly skin that worsens during cold, dry months. The diagnosis is usually clinical, but often aided with a skin biopsy showing hyperkeratosis and a diminished stratum granulosum. Emollients, moisturizers, keratolytics, and retinoids are the mainstays of management.

Condylomata acuminata are a clinical manifestation of genital HPV infection. Condylomata acuminata are described as raised, pearly, flesh-colored, papular, cauliflower-like lesions seen in the anogenital region that may cause itching, pain, or bleeding. Sexual contact is a common route of spread for HPV. While seen in all populations and ages, condylomata acuminata is most often seen in adolescence. HPV types 6 and 11 are responsible for 90% of warts and are considered low risk for malignancy; however, other types of HPV should be considered. Lesions rarely self-resolve; however, they can be removed via cryotherapy or topical antimitotic agents. While there is currently no treatment for HPV infection, it can be prevented through vaccination.

Vitiligo is the most common depigmenting disorder and is caused by the destruction of melanocytes. The etiology is unknown; however, genetic and autoimmune factors may play a role. Patients present with hypo- or depigmented macules or patches which often occur on the face, hands, knees, and/or genitalia. The diagnosis is clinical. Management depends on the severity and can include sun protection, topical or oral steroids, topical calcineurin inhibitors, immunosuppressants, and phototherapy.

Molluscum contagiosum is a viral infection limited to the epidermis and is common in children below 5 years of age. Lesions appear as grouped, flesh-colored, dome-shaped papules with central umbilication. Molluscum contagiosum is mild in immunocompetent patients and self resolves within months. Immunocompromised individuals present with extensive lesions and systemic disease, which require treatment. Molluscum contagiosum is highly transmissible; therefore, patient education is key in its management. Cryotherapy with liquid nitrogen is the 1st-line treatment.

Bullous pemphigoid and pemphigus vulgaris are two different blistering autoimmune diseases. In bullous pemphigoid, autoantibodies attack the hemidesmosomes, which connect epidermal keratinocytes to the basement membrane. This attack results in large, tense subepidermal blisters. In pemphigus vulgaris, autoantibodies attack the desmosomal proteins, which connect the keratinocytes to one another. This attack results in a more severe, potentially fatal condition with fragile, flaccid blisters, usually with significant mucosal involvement. Diagnosis is made with biopsy and IF staining to identify and localize the antibodies. Management involves immunosuppression with corticosteroids and other steroid-sparing immunomodulatory agents.

Alopecia is the loss of hair in areas anywhere on the body where hair normally grows. Alopecia may be defined as scarring or non-scarring, localized or diffuse, congenital or acquired, reversible or permanent, or confined to the scalp or universal; however, alopecia is usually classified using the 1st 3 factors. The etiologies of alopecia are usually divided into disorders in which the hair follicle is abnormal or damaged and those in which the hair follicle is normal but the cycling of hair growth is abnormal. The most common presentations are androgenetic hair loss, alopecia areata, traction alopecia, tinea capitis, and telogen effluvium. Diagnosis is made through a positive medical history and physical exam findings. Treatment depends on the type and potential for regrowth.

Nevi (singular nevus), also known as “moles,” are benign neoplasms of the skin. Nevus is a non-specific medical term because it encompasses both congenital and acquired lesions, hyper- and hypopigmented lesions, and raised or flat lesions. Additionally, nevi can be found within different depths of the layers of the skin and originate from various types of cells (e.g., melanocytic, connective tissue, vascular). Nevi also have a wide variety of characteristic forms, which must be well understood in order to differentiate nevi from malignant melanoma. In this concept page, we will cover the basic classifications and most common types of nevi as well as the clinical criteria used to assess them.

Lichen planus (LP) is an idiopathic, cell-mediated inflammatory skin disease. It is characterized by pruritic, flat-topped, papular, purple skin lesions commonly found on the flexural surfaces of the extremities. Other areas affected include genitalia, nails, scalp, and mucous membranes. Exact etiology is unknown but has been found to be associated with hepatitis C infection, other diseases, and multiple drugs. Skin biopsy of the most prominent lesion is used for confirmation of the diagnosis. Cutaneous LP usually resolves in 1–2 years. Other forms, however, are chronic and persistent. Topical corticosteroids are the preferred treatment.

Erythema nodosum is an immune-mediated panniculitis (inflammation of the subcutaneous fat) caused by a type IV (delayed-type) hypersensitivity reaction. It commonly manifests in young women as tender, erythematous nodules on the shins. The underlying etiology varies and may be associated with infection, drug exposure, irritable bowel disease, pregnancy, or malignancy. The lesions often self-resolve within 8 weeks without scarring. Management focuses on identifying and treating the underlying cause.

Erythema multiforme (EM) is an acute hypersensitivity reaction characterized by targetoid skin lesions with multiple rings and dusky centers. Lesions may be accompanied by systemic symptoms (e.g., fever) and mucosal lesions (e.g., bullae). The majority of patients with EM have a history of recent viral (especially herpes simplex virus) or bacterial infection (usually Mycoplasma pneumoniae). Erythema multiforme is diagnosed clinically and treatment is directed toward the causative agent and alleviation of symptoms.