Primary Myelofibrosis
Overview Definition Primary myelofibrosis (PMF) is a chronic myeloproliferative neoplasm characterized by proliferation of myeloid cells, with nonclonal fibroblast proliferation and hyperactivity, resulting in an obliterative marrow fibrosis. Other names include chronic idiopathic myelofibrosis and agnogenic myeloid metaplasia. Epidemiology Etiology Pathophysiology Hematopoiesis Hematopoiesis starts with the hematopoietic stem cell, which is prompted to divide and […]
Lymphocytosis
Overview Definition Lymphocytosis refers to elevated levels of lymphocytes. This elevation most often results from increased production. Lymphocyte subsets Epidemiology Etiology and Pathophysiology Lymphocytosis may result from an increased production of lymphocytes (most common) or several additional mechanisms. Increased production of lymphocytes The production of lymphocytes may be increased because of: Table: Infectious processes associated […]
Malassezia Fungi
General Characteristics and Epidemiology General features of Malassezia Clinically relevant species There are a number of recognized species: Associated diseases Epidemiology Tinea versicolor: Malassezia folliculitis: Pathogenesis Reservoir Malassezia are part of the normal skin flora in humans and animals. Host risk factors Predisposing risk factors for disease include: Pathophysiology Tinea versicolor: Seborrheic dermatitis: Malassezia folliculitis: […]
Chronic Obstructive Pulmonary Disease (COPD)
Overview Definition Chronic obstructive pulmonary disease (COPD) is a lung disease characterized by airflow limitation resulting from airway disease and/or parenchymal destruction. Types The subtypes may have differing presentations and response to therapy. Patients may have any combination of both. Epidemiology Etiology Risk factors Pathophysiology Chronic bronchitis Inhaled agents cause chronic inflammation in the airways, […]
Hypernatremia
Water Regulation Water regulation is controlled by the interplay between the osmoreceptors in the hypothalamus and the response to antidiuretic hormone (ADH) in the kidneys, resulting in very tight control of serum sodium and plasma osmolality. Hypothalamic osmoreceptors Response to ADH in the kidney Etiology Etiologies of hypernatremia are organized according to volume status. Hypervolemic […]
Equine Encephalitis Viruses
Classification General Characteristics and Epidemiology General features of equine encephalitis virus (EEV) Family: Togaviridae Genus: Alphavirus Genome: Positive-sense, ssRNA 11–12 kb in size Properties: Enveloped Lipid bilayer envelope has viral-encoded glycoproteins E1 and E2. Small icosahedral capsid Clinically relevant viruses and geographic distribution: Eastern equine encephalitis virus (EEEV) complex: Eastern equine encephalitis (EEE) virus: North […]
Rupture of the Spleen
Overview Definition Splenic rupture is often associated with trauma (e.g., motor vehicle accident) that causes a laceration of the organ. Epidemiology Etiology Pathophysiology Splenic rupture can have serious consequences because of the unique physiologic function of the spleen. Clinical Presentation History Physical examination Diagnosis Physical examination and history may be useful, but not all patients […]
Antiphospholipid Syndrome
Overview Definition Antiphospholipid syndrome (APS) is an autoimmune phenomenon that presents with thrombotic events and/or adverse pregnancy outcomes related to the presence of persistent antiphospholipid antibodies (aPL), which produce a hypercoagulable state. Epidemiology In the United States: Classification Patients with APS are classified based on their clinical manifestations. Table: Classification of APS Classification Patients present […]
Insulinomas
Definition and Epidemiology Definition Insulinomas are pancreatic neuroendocrine tumors that are derived from beta cells and secrete insulin. Epidemiology Pathophysiology Normal insulin physiology Synthesis: Regulation: Release: Function: Pathophysiology of insulinomas Clinical Presentation Patients generally present with fasting hypoglycemia, which may manifest in episodes of sympathetic stimulation and/or central nervous system disturbances. Diagnosis Whipple triad A […]
Meningitis
Overview Definition Meningitis is inflammation of the protective membranes of the brain and the spinal cord, collectively called the meninges, that is commonly caused by an acute infection. Epidemiology Etiology Meningitis can be of infectious (most common) or noninfectious origin. Infectious meningitis can be community- or hospital-acquired. Infectious meningitis Bacterial meningitis: Viral meningitis: Fungal meningitis: Parasitic […]