Medical terms, defined.

Carfilzomib is a second-generation, irreversible proteasome inhibitor used to treat relapsed/refractory multiple myeloma. It works by blocking the 26S proteasome, leading to accumulation of misfolded/pro-apoptotic proteins and cancer cel...

Bivalirudin is a direct thrombin inhibitor (DTI) used as a parenteral anticoagulant, commonly in patients undergoing percutaneous coronary intervention (PCI), especially those with heparin-induced thrombocytopenia (HIT). It directly bind...

Allantoin is a keratolytic and skin-protectant compound naturally found in comfrey root and produced as a purine metabolite (breakdown product of uric acid) in most mammals except humans and higher primates. In humans, it is used topical...

Lactobacillus is a genus of gram-positive, rod-shaped, facultative/obligate anaerobic bacteria that are major components of the normal vaginal, GI, and oral flora. They produce lactic acid, which maintains a low vaginal pH (~3.5-4.5) tha...

Uricases (urate oxidases) are enzymes that catalyze the oxidation of uric acid to allantoin, a more water-soluble compound that is easily excreted. Humans lack a functional uricase gene (pseudogene), making uric acid the final product of...

Filamentous hemagglutinin (FHA) is a major virulence factor and adhesin produced by Bordetella pertussis, the causative agent of whooping cough. It mediates attachment of the bacterium to ciliated respiratory epithelial cells, facilitati...

Cord factor (trehalose dimycolate) is a glycolipid virulence factor found in the cell wall of Mycobacterium tuberculosis. It inhibits neutrophil migration, disrupts normal phagosome-lysosome fusion, and causes serpentine (cord-like) grow...

Protective antigen (PA) is the 83-kDa cell-binding component of Bacillus anthracis toxins and is common to both lethal toxin and edema toxin. It binds host cell receptors (ANTXR1/TEM8 and ANTXR2/CMG2), is cleaved by furin, and forms a he...

CD15 (Lewis X antigen, SSEA-1) is a carbohydrate cell surface marker classically used as an immunohistochemical marker for Reed-Sternberg cells in classic Hodgkin lymphoma. It is also expressed on granulocytes and monocytes, making it us...

CD30 is a cell surface marker (TNF receptor superfamily member) classically expressed on Reed-Sternberg cells in Classic Hodgkin Lymphoma and on neoplastic cells in Anaplastic Large Cell Lymphoma (ALCL). It is also used as a target for t...

Antitumor antibiotics are chemotherapeutic agents derived from Streptomyces species that interfere with DNA structure/function to kill rapidly dividing cancer cells. Key drugs include anthracyclines (doxorubicin, daunorubicin), bleomycin...

Idarubicin is an anthracycline chemotherapeutic agent, most commonly used in the treatment of acute myeloid leukemia (AML), often in combination with cytarabine (7+3 regimen). Like other anthracyclines, its major dose-limiting toxicity i...

Daunorubicin is an anthracycline chemotherapy agent used primarily in acute leukemias (AML, ALL). It works by intercalating into DNA, inhibiting topoisomerase II, and generating free radicals, leading to DNA strand breaks and apoptosis o...

Actinomycin D (dactinomycin) is a chemotherapeutic antibiotic that intercalates into DNA, inhibiting RNA polymerase and blocking transcription. It is primarily used to treat pediatric cancers such as Wilms tumor, rhabdomyosarcoma, and Ew...

-rubicin is a suffix denoting anthracycline antibiotics used as chemotherapeutic agents, derived from Streptomyces bacteria. Examples include doxorubicin, daunorubicin, epirubicin, and idarubicin. These drugs intercalate DNA and inhibit...

Dactinomycin (Actinomycin D) is a chemotherapeutic antibiotic that intercalates into DNA to inhibit RNA polymerase and transcription. It is classically used in pediatric tumors like Wilms tumor, rhabdomyosarcoma, and Ewing sarcoma, often...

Anergy refers to a state of diminished or absent immune reactivity, where immune cells (typically T cells) fail to respond to antigens they should recognize. It can refer to clinical anergy (lack of delayed-type hypersensitivity skin tes...

The nitroblue tetrazolium (NBT) test evaluates NADPH oxidase function in neutrophils, used to diagnose Chronic Granulomatous Disease (CGD). In normal neutrophils, NBT turns blue when reduced by superoxide; in CGD, there is no color chang...

The dihydrorhodamine (DHR) assay is a flow cytometry test used to diagnose chronic granulomatous disease (CGD), a primary immunodeficiency caused by defective NADPH oxidase. It measures the oxidative burst capacity of neutrophils by asse...

Conjunctival injection refers to dilation and engorgement of the superficial conjunctival blood vessels, producing visible redness of the eye (ocular 'redness'). It is a nonspecific sign seen in conditions ranging from benign viral conju...

Eosin-5-maleimide (EMA) is a fluorescent dye used in the EMA-binding test, a flow cytometry-based assay to help diagnose hereditary spherocytosis (HS). It covalently binds to band 3 protein (and other membrane proteins) on red blood cell...

Acrolein is the toxic metabolite of cyclophosphamide and ifosfamide responsible for hemorrhagic cystitis. It is formed during hepatic metabolism of these alkylating agents and is excreted in urine, where it directly damages bladder uroth...

Sick sinus syndrome (SSS) refers to a group of sinoatrial (SA) node dysfunctions causing inappropriate bradycardia, sinus pauses/arrest, or alternating bradycardia-tachycardia (tachy-brady syndrome). It is most common in elderly patients...

Polymyxins (polymyxin B and colistin/polymyxin E) are cationic polypeptide antibiotics that act as detergents on bacterial cell membranes, used as last-line agents against multidrug-resistant (MDR) gram-negative organisms. They are nephr...

β-lactams are a major class of antibiotics characterized by a core β-lactam ring, which inhibits bacterial cell wall synthesis by binding penicillin-binding proteins (PBPs). This class includes penicillins, cephalosporins, carbapenems, a...

Pseudo-Pelger-Huet anomaly refers to acquired hyposegmentation of neutrophil nuclei (bilobed or 'pince-nez' shaped nuclei) that mimics the inherited Pelger-Huet anomaly but arises secondary to myelodysplastic syndrome (MDS), chemotherapy...

A leukoerythroblastic smear refers to the presence of immature white blood cells (myelocytes, metamyelocytes) and nucleated red blood cells (erythroblasts) in the peripheral blood, along with teardrop cells (dacrocytes). It indicates mar...

Pseudo-Pelger-Huët anomaly refers to acquired hyposegmentation of neutrophil nuclei (bilobed, 'pince-nez' or dumbbell-shaped) that mimics the inherited Pelger-Huët anomaly but occurs secondary to an underlying disorder, most commonly mye...

Ruxolitinib is a JAK1/JAK2 inhibitor used primarily to treat myeloproliferative neoplasms, especially myelofibrosis and polycythemia vera resistant to hydroxyurea. It also has an FDA-approved indication for steroid-refractory acute graft...

Erythromelalgia is a rare condition characterized by episodic, severe burning pain, erythema, and warmth of the extremities (typically feet and hands), classically triggered by heat and relieved by cooling. It is strongly associated with...

Anti-β2-glycoprotein I antibodies are a subtype of antiphospholipid antibodies associated with antiphospholipid syndrome (APS). They target β2-glycoprotein I, a plasma protein that binds phospholipids, and contribute to a hypercoagulable...

Anti-cardiolipin antibodies are antiphospholipid antibodies associated with antiphospholipid syndrome (APS), causing a hypercoagulable state. They can cause both arterial and venous thrombosis, recurrent pregnancy loss, and a paradoxical...

Pectus carinatum, or 'pigeon chest,' is a congenital chest wall deformity characterized by anterior protrusion of the sternum and costal cartilages. It is less common than pectus excavatum and often associated with connective tissue diso...

Dyskinesia refers to abnormal, involuntary muscle movements that can include tics, jerks, tremors, or writhing motions. It is commonly seen as a side effect of long-term dopaminergic therapy (e.g., levodopa in Parkinson's disease) or ant...

Bradykinesia refers to slowness of voluntary movement and a progressive reduction in amplitude and speed during repetitive actions. It is a cardinal feature of Parkinson disease and parkinsonian syndromes, resulting from dopaminergic neu...

Trabecular refers to the spongy, lattice-like meshwork of bone (trabecular/cancellous bone) found at the ends of long bones and within vertebral bodies, as well as similar meshwork structures in other tissues like the spleen, lymph nodes...

Endochondral ossification is the process by which bone forms from a pre-existing hyaline cartilage model, responsible for the formation of most long bones and bones of the axial and appendicular skeleton. It is essential for longitudinal...

Zoledronic acid is a potent third-generation IV bisphosphonate used to treat osteoporosis, hypercalcemia of malignancy, Paget's disease of bone, and bone metastases from solid tumors (e.g., breast, prostate) and multiple myeloma. It inhi...

Alendronate is a nitrogen-containing bisphosphonate used primarily to treat osteoporosis and other conditions of bone resorption like Paget's disease. It inhibits osteoclast-mediated bone resorption by binding hydroxyapatite and disrupti...

Pamidronate is an intravenous nitrogen-containing bisphosphonate used to treat hypercalcemia of malignancy, osteolytic bone lesions from metastases or multiple myeloma, and Paget's disease of bone. It works by inhibiting osteoclast-media...

Osteitis fibrosa cystica (also called von Recklinghausen disease of bone) is a skeletal manifestation of severe hyperparathyroidism, caused by excessive osteoclastic bone resorption due to elevated PTH. It is characterized by subperioste...

SVR (Systemic Vascular Resistance) is the resistance offered by the systemic vasculature to blood flow, primarily determined by arteriolar tone. It is a key determinant of blood pressure (BP = CO x SVR) and is used clinically to classify...

Pannus is an abnormal layer of inflammatory granulation tissue that invades and destroys cartilage and bone, classically seen in rheumatoid arthritis. It forms from proliferating synoviocytes, fibroblasts, and inflammatory cells, driven...

Mucosal neuromas are benign, painless, pink/flesh-colored nodules composed of proliferated nerve tissue found on the lips, tongue, and buccal mucosa. They are a classic hallmark of Multiple Endocrine Neoplasia type 2B (MEN2B), often one...

Seronegative spondyloarthritis (SpA) is a group of inflammatory arthritides characterized by axial and/or peripheral joint involvement, enthesitis, and absence of rheumatoid factor (RF) and anti-CCP antibodies. Strongly associated with H...

Clofazimine is a fat-soluble riminophenazine antibiotic used primarily in multidrug therapy for leprosy (Hansen's disease) and increasingly for multidrug-resistant tuberculosis. It has both antimicrobial and anti-inflammatory properties,...

Anencephaly is a severe neural tube defect resulting from failure of the rostral (cephalic) neuropore to close during the 4th week of embryonic development, leading to absence of major portions of the brain, skull, and scalp. It is incom...

Anti-U1 RNP (ribonucleoprotein) antibodies are autoantibodies directed against the U1-RNP complex involved in mRNA splicing. They are the serologic hallmark of Mixed Connective Tissue Disease (MCTD), where they are found in high titers,...

Speckled ANA is an immunofluorescence pattern of antinuclear antibody testing characterized by fine or coarse granular staining throughout the nucleoplasm, excluding the nucleoli. It is the least specific ANA pattern, seen in multiple au...

Mixed connective tissue disease (MCTD) is an overlap autoimmune disorder featuring clinical features of SLE, systemic sclerosis, and polymyositis, characterized serologically by high-titer anti-U1 ribonucleoprotein (anti-RNP) antibodies....