AOBPa Pathology key terms

Cell death in which proteins denature and cytoplasm becomes glassy and firm while tissue architecture is briefly preserved; classically caused by ischemia in heart, kidney, and spleen.

Cell death in which enzymes digest dead tissue into a liquid viscous mass; typical of brain infarcts and bacterial abscesses where neutrophils release hydrolytic enzymes.

A form of necrosis with friable, cheese-like, structureless eosinophilic material, most often seen in granulomatous infection such as tuberculosis.

Programmed, energy-dependent cell death producing membrane-bound apoptotic bodies that are cleared without inflammation; regulated by caspases and Bcl-2 family proteins.

Reversible replacement of one mature differentiated cell type with another better suited to a stressor, such as squamous metaplasia of bronchial epithelium in smokers.

Disordered growth with loss of uniformity and orientation of cells, nuclear atypia, and increased mitoses; a precancerous change that may progress to malignancy.

A compact aggregate of epithelioid macrophages, often with multinucleated giant cells and a rim of lymphocytes, formed in response to persistent antigens such as mycobacteria or foreign material.

Ischemic necrosis of tissue resulting from occlusion of arterial supply or venous drainage; morphology depends on organ, vessel size, and collateral circulation.

Pathologic formation of a blood clot within an intact vessel or cardiac chamber, promoted by endothelial injury, abnormal blood flow, and hypercoagulability (Virchow triad).

An intravascular mass, commonly a detached thrombus, fat, air, or tumor fragment, that travels in the bloodstream and lodges in a distant vessel.

Misfolded, insoluble fibrillar protein deposited extracellularly in beta-pleated sheets; stains apple-green birefringent with Congo red under polarized light.

Excessive deposition of collagen-rich scar tissue replacing parenchyma after injury, impairing organ function; driven largely by activated fibroblasts and myofibroblasts.

Automated measurement of red cell, white cell, and platelet counts plus indices such as hemoglobin, hematocrit, and mean corpuscular volume; the first-line hematologic screening test.

Microscopic examination of stained blood on a slide to assess cell morphology, differential leukocyte count, and platelet adequacy when automated results are abnormal.

Reduction in hemoglobin or red cell mass below reference range, classified by mean corpuscular volume as microcytic, normocytic, or macrocytic to guide further testing.

Percentage or absolute number of newly released immature red cells, used to judge whether marrow is responding appropriately to anemia.

Central range of test results, typically covering 95% of a healthy reference population, against which a patient value is compared; varies with age, sex, and method.

Routine analysis of known control materials alongside patient samples to verify that a laboratory method performs within predefined limits before results are reported.

Sensitivity is the proportion of truly diseased persons testing positive; specificity is the proportion of truly healthy persons testing negative; both describe test discrimination independent of prevalence.

The probability that a positive or negative test result is correct in a given population; unlike sensitivity and specificity, it changes with disease prevalence.

Rapid intraoperative tissue preparation by freezing, sectioning, and staining, used mainly to establish diagnosis, margin status, or adequacy of tissue during surgery.

Macroscopic description and sampling of a specimen, recording size, color, consistency, and relationship to margins to guide representative histologic sections.

Assessment of whether tumor extends to the surgically cut edge of a specimen; a positive margin indicates tumor at the inked surface and raises local recurrence risk.

Fibrotic stromal reaction induced by infiltrating carcinoma, producing a firm, retracted, scar-like texture on gross examination and dense collagen on microscopy.

Presence of tumor cells within endothelial-lined lymphatic or blood vessel spaces, a feature that correlates with metastatic risk and is reported in many cancer resections.

The first draining lymph node(s) from a tumor, identified by dye or radiotracer and examined to stage regional metastasis without removing the entire nodal basin.

Polychrome cytologic stain producing distinct nuclear chromatin detail and differential cytoplasmic colors, widely used for cervical and other exfoliative cytology preparations.

Cytology preparation method in which cells are collected in preservative fluid, then processed to yield a thin, uniform monolayer with reduced obscuring blood and mucus.

Minimally invasive sampling of a mass using a thin needle and suction to obtain cells for cytologic evaluation, often with rapid on-site adequacy assessment.

Judgment of whether a cytologic or biopsy sample contains sufficient, well-preserved diagnostic material; an inadequate result is reported as such rather than as negative.

Relative area of nucleus compared with cytoplasm; a high ratio with irregular nuclear contours is a cytologic feature suggesting malignancy.

Paired procedures: aspirate smears assess cell morphology and counts, while the core biopsy evaluates cellularity, architecture, and infiltration; interpreted together.

Clonal stem cell disorder with ineffective hematopoiesis, cytopenias, and dysplastic morphology in one or more lineages, carrying risk of progression to acute myeloid leukemia.

Percentage of immature hematopoietic precursor cells in marrow or blood; thresholds are used to separate myelodysplasia and chronic disorders from acute leukemia.

Stacking of red cells like coins on a smear, caused by increased plasma proteins such as immunoglobulins or fibrinogen, and classically associated with plasma cell dyscrasias.

Presence of a single clonal immunoglobulin or light chain detectable as a serum or urine spike on electrophoresis, produced by a clonal plasma cell or B-cell population.

Technique that amplifies a targeted DNA segment through repeated cycles of denaturation, primer annealing, and extension, allowing detection of small amounts of specific sequence.

Method using fluorescently labeled probes that bind specific chromosomal sequences in intact nuclei, detecting deletions, amplifications, and translocations without culturing cells.

Chain-termination DNA sequencing using labeled dideoxynucleotides, producing a readout of a single targeted region; the classic reference method for confirming point variants.

Ordered display of an individual's chromosomes after banding, revealing numerical and large structural abnormalities such as translocations visible by light microscopy.

Structural chromosomal rearrangement in which a segment of one chromosome joins another, potentially creating a fusion gene with oncogenic activity.

A genetic alteration whose association with disease is unproven; it should not be used alone to make clinical management decisions and may be reclassified as evidence accrues.

Germline variants are inherited and present in nearly all cells; somatic variants arise in a tissue and are absent from normal cells, affecting interpretation and family risk.

Differential stain that divides bacteria by cell wall structure into gram-positive (purple) and gram-negative (pink) organisms and shows their morphology and arrangement.

Growth of an organism from a specimen followed by testing its susceptibility to antimicrobial agents, guiding targeted therapy and resistance surveillance.

Localized collection of pus within tissue, with liquefactive necrosis, abundant neutrophils, and a surrounding wall of granulation tissue and fibrosis.

Large multinucleated cell formed by fusion of macrophages, seen in granulomas and foreign body reactions, or of other lineages in specific lesions.

Practices that prevent contamination of specimens, wounds, and cultures, including hand hygiene, barriers, and disinfection of collection sites.

Impaired or altered function of related components of the somatic system, identified by TART findings: tissue texture change, asymmetry, restricted motion, and tenderness.

Systematic regional assessment of the musculoskeletal system for somatic dysfunction, integrating posture, motion testing, and palpation into the patient's overall clinical evaluation.

Facilitated spinal cord segment activity in which visceral disease produces referred somatic findings such as paraspinal tissue texture change and tenderness at related levels.

Osteopathic manipulative technique using rhythmic compression and release of the thorax or extremities to promote lymphatic and venous return and reduce edema.