Myelodysplastic Syndromes
Overview Definition Myelodysplastic syndromes (MDS) are clonal, bone marrow diseases characterized by the presence of dysplastic, immature, bone marrow precursors and peripheral cytopenias. The World Health Organization (WHO) published an update in 2022 in which it renamed myelodysplastic syndromes “Myelodysplastic neoplasms (MDS)”. Epidemiology Etiology Pathophysiology The majority of MDS is attributed to chromosomal deletions and […]
Sexually Transmitted Infections (STIs)
Epidemiology 26 million new STIs diagnosed in the United States in 2018 High-risk patient groups: Adolescents and young adults ages 15–24 years (accounted for 50% of new STIs in 2018) Men who have sex with men (MSM) Racial and ethnic minorities HSV-2 and syphilis increase HIV infection risk. STIs can result in serious reproductive consequences […]
Electrolytes
Introduction Body fluids and electrolytes Electrolyte balance The ICF and ECF compartments have different and unequal electrolyte distribution to maintain physiological function. Intracellular fluid: Extracellular fluid: Sodium Overview Regulation Related disorders Potassium Overview Regulation Related disorders Chloride Overview Regulation Chloride homeostasis: Related disorders Calcium Overview Regulation Related disorders Magnesium Overview Regulation Related disorders Phosphate Overview […]
Acute Otitis Media
Overview Definition Acute otitis media is an infection characterized by the accumulation of fluid and inflammation within the middle ear. Epidemiology Etiology Acute otitis media is an inflammatory condition of the middle ear with an infectious etiology that may be bacterial (most common) or viral. Causes include: Bacterial: Viral: Risk factors Pathophysiology and Clinical Presentation […]
Herpes Zoster (Shingles)
Overview Definition Herpes zoster (also known as shingles) is a viral, reactivation infection caused by the varicella-zoster virus (VZV) manifesting as a unilateral, dermatomal, painful, vesicular eruption. Epidemiology Etiology Causative organism: VZV Transmission: Risk factors Pathophysiology Varicella-zoster virus causes 2 distinct syndromes: Primary infection (chickenpox): Secondary infection (shingles): Clinical Presentation and Complications Common presentation Acute […]
Neutropenia
Overview Definition Neutropenia is a decrease in the number of circulating neutrophils in the blood, which is typically defined as an absolute neutrophil count (ANC) of: Neutrophils Neutrophils are the most common of all the leukocytes. Leukocytes are WBCs and are a major component of the immune system. Table: Normal ANC levels by age Age […]
Anemia: Overview and Types
Overview Definition Anemia is a quantitative deficiency of Hb, the oxygen-carrying component of RBCs. Anemia is noted when Hb levels are approximately: Normal levels can vary depending on the laboratory reference range. Epidemiology Anatomy and physiology review Etiology Anemia can be caused by: Classification of anemia according to etiology Table: Classification of anemia according to […]
Autoimmune Hemolytic Anemia
Overview Definition Autoimmune hemolytic anemia (AIHA) is hemolysis or premature destruction of RBCs due to autoantibodies. There are 2 categories of AIHA based on the thermal reactivity of autoantibodies: Epidemiology Etiology Warm AIHA: Cold AIHA: Mixed-type AIHA: Specific causes of AIHAs Table: Specific causes of warm AIHA (antibody type mostly IgG) Type Specific cause Primary […]
Hodgkin Lymphoma
Overview Definition Hodgkin lymphoma (HL) is a monoclonal B-cell lymphoma (neoplasm) originating in lymph nodes in which the malignant Hodgkin/Reed-Sternberg (HRS) cells are mixed with a heterogeneous population of nonneoplastic inflammatory cells. Epidemiology Etiology Classification Based on WHO classification, HLs have the following types and subtypes according to immunophenotype and morphology. Classic HL (95%): Nodular […]
Essential Thrombocythemia
Overview Definition Essential thrombocythemia (ET) is a chronic myeloproliferative neoplasm characterized by excessive platelet production and increased thrombotic and hemorrhagic tendency. Other names are essential thrombocytosis and primary thrombocytosis. Epidemiology Incidence: 1–2.5 cases per 100,000 in the United States Incidence increases with age (median age at diagnosis: 60 years) Female:male ratio of 2:1 Etiology Proliferation of […]