Iraqi Board Pathology cheat sheet

Reversible cell injury: ATP depletion, cell swelling, ribosomal detachment, blebbing; irreversible once membrane integrity is lost and mitochondrial permeability transition pores open.

Coagulative necrosis: preserved tissue architecture, eosinophilic anucleate cells; typical of ischemic myocardium, kidney, spleen. Caseous necrosis: friable granular center with granulomatous rim (TB).

Apoptosis vs necrosis: apoptosis is energy-dependent, caspase-mediated (caspase-3 executioner), non-inflammatory, with phosphatidylserine externalization detected by annexin V.

Acute inflammation: vasodilation, increased vascular permeability (endothelial contraction, direct injury, leukocyte-mediated), neutrophil-predominant first 6-24 hours; macrophages dominate after 48 hours.

Granuloma: collection of activated macrophages (epithelioid cells) with Langhans giant cells, surrounded by lymphocytes and fibrosis; caused by TB, sarcoidosis, foreign body, fungi.

Wound healing: primary intention has minimal granulation tissue; secondary intention has more contraction and scarring. Collagen type III is laid down first, replaced by type I; vitamin C needed for hydroxylation.

Neoplasia: benign tumors are well-circumscribed, non-invasive, non-metastatic; malignant tumors show invasion, metastasis, anaplasia, pleomorphism, high mitotic rate, and tumor giant cells.

Tumor suppressor genes: RB (retinoblastoma), TP53 (Li-Fraumeni), APC (FAP), BRCA1/2, NF1/2, VHL. Oncogenes: RAS, MYC, HER2, BCR-ABL, CCND1.

Virchow triad for thrombosis: endothelial injury, abnormal blood flow (stasis/turbulence), hypercoagulability. Lines of Zahn indicate antemortem thrombus.

Myocardial infarction: coagulative necrosis begins 4-12 hours, neutrophilic infiltrate 1-3 days, macrophage cleanup 3-7 days, granulation tissue 1-2 weeks, dense scar by 6-8 weeks.

Nephrotic syndrome: proteinuria >3.5 g/day, hypoalbuminemia, edema, hyperlipidemia. Nephritic syndrome: hematuria, RBC casts, hypertension, oliguria, azotemia.

Cirrhosis: bridging fibrous septa with regenerative nodules; complications include portal hypertension, varices, ascites, hepatic encephalopathy, and hepatocellular carcinoma.

Peptic ulcer disease: H. pylori in ~70% of gastric and ~95% of duodenal ulcers; NSAIDs and Zollinger-Ellison syndrome are other major causes.

Atherosclerosis: intimal plaque with lipid core, foam cells, fibrous cap; unstable plaque has thin cap, large necrotic core, and inflammatory infiltrate.

Chronic obstructive pulmonary disease: emphysema (centriacinar in smokers, panacinar in alpha-1 antitrypsin deficiency) plus chronic bronchitis (cough with sputum ≥3 months for 2 consecutive years).

Diabetic nephropathy: Kimmelstiel-Wilson nodules, mesangial expansion, thickened glomerular basement membrane; earliest change is microalbuminuria.

Thyroid: papillary carcinoma shows Orphan Annie nuclei, nuclear grooves, psammoma bodies; follicular carcinoma shows capsular/vascular invasion; medullary carcinoma secretes calcitonin and shows amyloid stroma.

Frozen section indications: intraoperative diagnosis (margin status, lymph node metastasis, unknown lesion), tissue triage for banking; avoid for fat, bone, and lymphoid lesions requiring permanent processing.

Margin reporting: invasive carcinoma uses closest margin distance in mm; DCIS uses 2 mm as adequate for breast-conserving surgery; basal cell carcinoma uses peripheral and deep margin assessment.

Breast carcinoma grading (Nottingham): tubule formation, nuclear pleomorphism, mitotic count, each scored 1-3; total 3-5 = grade 1, 6-7 = grade 2, 8-9 = grade 3.

Colorectal carcinoma staging: T1 invades submucosa, T2 muscularis propria, T3 through muscularis propria into subserosa, T4 invades other organs or visceral peritoneum.

Prostate adenocarcinoma: Gleason score sums the two most prevalent patterns (1-5 each); Grade Group 1 = Gleason 3+3 = 6, Grade Group 5 = Gleason 9-10.

Lymph node processing: nodes <0.5 cm submitted whole; larger nodes bivalved along long axis; fatty tissue cleared for small nodes in melanoma and breast cancer.

Immunohistochemistry panels: cytokeratin (carcinoma), vimentin (sarcoma), CD45 (lymphoma), S100/SOX10 (melanoma), synaptophysin/chromogranin (neuroendocrine).

Frozen section artifacts: freezing artifact (nuclear ice crystals), chatter, and cautery artifact; formalin fixation before freezing prevents freezing artifact.

Specimen orientation: ink margins before sectioning; use multiple colors for distinct margins; record inks and orientation in the gross description.

Bethesda cervical cytology: NILM, ASC-US, LSIL, ASC-H, HSIL, AGC, AIS, carcinoma, unsatisfactory; ASC-US triggers HPV triage or repeat in 1 year.

HPV testing: high-risk types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66, 68; co-testing recommended for women 30-65 years.

Koilocytosis: perinuclear halo, enlarged nucleus, raisin-like nuclear contour; hallmark of HPV cytopathic effect (LSIL).

Thyroid FNA Bethesda categories: I nondiagnostic, II benign, III AUS/FLUS, IV follicular neoplasm, V suspicious for malignancy, VI malignant; risk of malignancy rises from ~5-15% (III) to ~97-99% (VI).

Salivary gland FNA: pleomorphic adenoma shows fibrillary chondromyxoid stroma and plasmacytoid cells; Warthin tumor shows oncocytes with lymphocytes.

Serous effusion: malignant cells show high N/C ratio, irregular nuclear membranes, prominent nucleoli, and cell clusters; reactive mesothelial cells have two-toned cytoplasm and windows.

Fine needle aspiration of lymph nodes: granulomatous inflammation, metastatic carcinoma, and lymphoma are the main categories; flow cytometry improves lymphoma diagnosis.

Urine cytology: high-grade urothelial carcinoma shows pleomorphic cells with prominent nucleoli and irregular chromatin; Paris System categories include AUC, SHGUC, and HGUC.

Cell block preparation allows immunohistochemistry and molecular testing on cytology specimens; useful for lung adenocarcinoma and effusion samples.

Anemia classification by MCV: microcytic (<80 fL) - iron deficiency, thalassemia, anemia of chronic disease; macrocytic (>100 fL) - B12/folate deficiency, alcohol, hypothyroidism, MDS.

Iron studies: iron deficiency shows low ferritin, low serum iron, high TIBC, low saturation; anemia of chronic disease shows normal/high ferritin, low iron, low TIBC.

CML: t(9;22) BCR-ABL1; peripheral blood shows leukocytosis with full myeloid spectrum and basophilia; treated with imatinib.

Acute leukemia: ≥20% blasts in marrow or blood; AML shows myeloperoxidase and Auer rods; ALL shows TdT and CD19/CD10 (B-ALL).

Lymphoma: Hodgkin shows Reed-Sternberg cells (CD15+, CD30+, CD45-) in appropriate background; non-Hodgkin is classified by cell lineage and grade.

Multiple myeloma: ≥10% clonal plasma cells, M-protein, CRAB features (hypercalcemia, renal failure, anemia, bone lesions).

Coagulation: PT measures extrinsic and common pathway (factors VII, X, V, II, fibrinogen); aPTT measures intrinsic and common pathway (VIII, IX, XI, XII, X, V, II, fibrinogen).

DIC: prolonged PT and aPTT, low fibrinogen, elevated D-dimer, schistocytes on smear; treat underlying cause and support with FFP/platelets.

Bone marrow reporting: cellularity by age (100 minus age), M:E ratio normally 2:1 to 4:1; iron stores assessed on Prussian blue stain.

Reference intervals: statistically derived from central 95% of a healthy population; results outside do not automatically indicate disease.

Analytical imprecision: CV = (SD/mean) × 100; total allowable error often set as 1/2 to 1/3 of biological variation.

Tumor markers: AFP (hepatocellular carcinoma, yolk sac tumor), CEA (colorectal), CA 125 (ovarian), CA 19-9 (pancreatic), PSA (prostate).

Cardiac troponin I/T is the preferred biomarker for myocardial infarction; rises 3-6 hours after onset; high-sensitivity assays detect earlier.

Liver enzymes: ALT more liver-specific than AST; AST/ALT >2 suggests alcoholic liver disease; ALP and GGT rise in cholestasis.

Renal function: eGFR from creatinine (CKD-EPI equation); urea and creatinine rise in renal failure; potassium is the most critical electrolyte in renal failure.

Diabetes: fasting glucose ≥7.0 mmol/L, 2-hour OGTT ≥11.1 mmol/L, HbA1c ≥6.5% (48 mmol/mol) diagnose diabetes; HbA1c reflects 2-3 months of glycemia.

Lipids: LDL calculated by Friedewald formula when triglycerides <4.5 mmol/L; direct LDL measurement needed at higher triglycerides.

Blood gas: respiratory acidosis has low pH and high pCO2; metabolic acidosis has low pH and low HCO3; anion gap = Na − (Cl + HCO3), normal 8-12 mmol/L.

Gram stain: Gram-positive organisms retain crystal violet-iodine (thick peptidoglycan); Gram-negative decolorize and take safranin counterstain.

Acid-fast stain (Ziehl-Neelsen): detects Mycobacterium tuberculosis; auramine-rhodamine fluorescent stain is used for screening.

Culture media: blood agar (hemolysis patterns), MacConkey (Gram-negative lactose fermenters), chocolate agar (Haemophilus, Neisseria), Löwenstein-Jensen (mycobacteria).

Staphylococcus aureus: catalase positive, coagulase positive, mannitol fermenter; causes abscesses, endocarditis, toxic shock (TSST-1).

Streptococcus pyogenes: bacitracin sensitive, beta-hemolytic; complications include rheumatic fever and post-streptococcal glomerulonephritis.

Hepatitis serology: HBsAg indicates infection; anti-HBs indicates immunity; anti-HBc IgM indicates acute infection; HBeAg indicates high infectivity.

HIV: screen with fourth-generation antigen/antibody test; confirm with HIV-1/2 antibody differentiation; viral load for monitoring and diagnosis in acute infection.

Malaria: thick film for detection, thin film for species identification; Plasmodium falciparum shows banana-shaped gametocytes and high parasitemia.

Tuberculosis pathology: caseating granulomas with Langhans giant cells; acid-fast bacilli on Ziehl-Neelsen; culture remains the gold standard.

Hypersensitivity types: I IgE-mediated (anaphylaxis), II antibody-mediated (hemolysis, Goodpasture), III immune complex (SLE, post-streptococcal GN), IV T-cell mediated (contact dermatitis, TB).

ABO compatibility: O negative is universal donor for red cells; AB positive is universal recipient; plasma compatibility is reversed (AB donor, O recipient).

Crossmatch: immediate spin detects ABO incompatibility; antihuman globulin phase detects IgG antibodies; electronic crossmatch is allowed when valid historical blood type exists.

Transfusion reactions: febrile non-hemolytic (most common), acute hemolytic (ABO mismatch, fever, hemoglobinuria, DIC), TRALI (pulmonary edema within 6 hours), TACO (volume overload).

Autoimmune diseases: ANA is sensitive for SLE; anti-dsDNA and anti-Sm are specific; anti-histone suggests drug-induced lupus.

ANCA: c-ANCA (anti-PR3) in granulomatosis with polyangiitis; p-ANCA (anti-MPO) in microscopic polyangiitis and eosinophilic granulomatosis with polyangiitis.

Immunodeficiency: Bruton (X-linked agammaglobulinemia) shows absent B cells and low immunoglobulins; DiGeorge shows T-cell deficiency with hypocalcemia.

Direct Coombs test detects antibodies/complement on patient RBCs (autoimmune hemolysis, hemolytic disease of newborn); indirect Coombs detects antibodies in serum.

PCR: exponential amplification of target DNA; real-time PCR quantifies product with fluorescent probes; contamination control with uracil-N-glycosylase.

FISH: fluorescent probes detect gene amplifications (HER2), translocations (BCR-ABL, ALK), and deletions (1p/19q); requires intact nuclei.

Next-generation sequencing: massively parallel sequencing; detects mutations, fusions, copy number, and RNA expression; requires bioinformatic pipeline and variant classification.

EGFR mutations in lung adenocarcinoma predict response to tyrosine kinase inhibitors (gefitinib, erlotinib, osimertinib); T790M confers resistance.

KRAS mutations predict resistance to anti-EGFR antibodies (cetuximab, panitumumab) in colorectal carcinoma.

BRCA1/2 germline mutations increase breast and ovarian cancer risk; PARP inhibitors (olaparib) exploit synthetic lethality.

MSI/dMMR testing: microsatellite instability high or mismatch repair deficiency predicts response to immune checkpoint inhibitors and suggests Lynch syndrome.

Liquid biopsy: circulating tumor DNA detects mutations, monitors response, and identifies resistance; limited by low tumor fraction.

Karyotyping: detects numerical and structural chromosome abnormalities; resolution ~5-10 Mb; used for aneuploidy and translocations.

FISH: locus-specific probes for microdeletions (22q11.2), amplifications, and translocations; does not detect point mutations.

Sanger sequencing: gold standard for single-gene point mutations; limited throughput; detects variants present in ≥15-20% of cells.

Immunohistochemistry: antigen retrieval unmasks epitopes; controls include positive and negative tissue controls; interpretation requires appropriate antibody clone and dilution.

Electron microscopy: identifies desmosomes, microvilli, melanosomes, and viral particles; used for renal biopsy (immune deposits) and ciliary defects.

Inheritance patterns: autosomal dominant (50% risk, vertical transmission), autosomal recessive (25% risk, consanguinity), X-linked recessive (males affected, carrier females).

Prenatal diagnosis: chorionic villus sampling at 10-13 weeks; amniocentesis at 15-20 weeks; cell-free fetal DNA from maternal blood after 10 weeks.

Flow cytometry: identifies cell surface markers (CD antigens) for leukemia/lymphoma; immunophenotyping guides diagnosis and minimal residual disease monitoring.

Cause of death: disease or injury producing the fatal termination; manner of death: natural, accident, homicide, suicide, undetermined; mechanism: physiological derangement.

Rigor mortis: begins 1-2 hours after death, peaks at 12 hours, resolves by 24-36 hours; affected by temperature and muscle mass.

Livor mortis: dependent lividity begins 30 minutes to 2 hours after death, becomes fixed after 6-8 hours; helps determine body position.

Algor mortis: body cooling rate approximately 1-1.5 °C per hour under normal conditions; affected by ambient temperature, clothing, and body habitus.

Postmortem interval: estimated from body temperature, rigor, livor, gastric emptying, and entomology; no single method is reliable.

Autopsy types: hospital (clinical) autopsy for quality assurance and education; medicolegal autopsy for sudden, unexpected, or violent deaths.

Gunshot wounds: entrance wound shows abrasion collar and soot/tattooing if close range; exit wound is typically larger and everted.

Asphyxia: petechiae of conjunctiva and face, cyanosis, and congestion; ligature mark pattern helps distinguish hanging from strangulation.

Toxicology specimens: femoral blood preferred for quantitative analysis; vitreous humor for electrolytes and glucose; urine for drug screening.

Quality management system: organization, personnel, equipment, process control, documents, records, and continual improvement; ISO 15189 is the international standard for medical laboratories.

Turnaround time: pre-analytical, analytical, and post-analytical phases; most errors occur in the pre-analytical phase.

Staffing: workload-based staffing uses test volume and complexity; competency assessment required at hire, after training, and annually.

Budgeting: fixed costs (rent, salaried staff) versus variable costs (reagents, consumables); cost per test includes direct and indirect costs.

Inventory control: FIFO and FEFO rotation; reagent lot verification before use; monitor expiry dates and storage temperatures.

Lean and Six Sigma: reduce waste and variation; define, measure, analyze, improve, control (DMAIC) cycle for process improvement.

Accreditation versus certification: accreditation is formal recognition of competence by an authoritative body; certification validates conformity to requirements.

Risk management: failure mode and effects analysis (FMEA) prioritizes risks by severity, occurrence, and detection; root cause analysis for incidents.

Quality control: internal QC runs each shift with control materials; Westgard rules (1-3s, 2-2s, R-4s, 4-1s, 10x) flag random and systematic error.

External quality assessment: proficiency testing compares results with peer laboratories; unacceptable results require investigation and corrective action.

Pre-analytical errors: patient identification, tube type, order of draw, hemolysis, and transport time; order of draw for additive tubes follows CLSI sequence.

Post-analytical errors: reporting, reference range accuracy, critical value notification, and turnaround time; critical values must be reported and documented.

Ethics: informed consent, confidentiality, and conflict-of-interest disclosure; patient autonomy and beneficence guide decision-making.

Research ethics: institutional review board approval, informed consent, and data protection; Declaration of Helsinki governs human research.

Error disclosure: honest communication with patients about laboratory errors; root cause analysis and system improvement rather than individual blame.

Competency and continuing education: annual competency assessment, continuing professional development, and documented training records.