Arab Board Anatomic Pathology Part 1 cheat sheet

Apoptosis is caspase-dependent, preserves membrane integrity, and causes cell shrinkage and apoptotic bodies without inflammation; necrosis involves membrane rupture and inflammation.

Coagulative necrosis follows ischemia in heart, kidney, and spleen; liquefactive necrosis occurs in brain infarcts and abscesses; caseous necrosis in tuberculosis; fat necrosis in pancreatitis; fibrinoid necrosis in vasculitis.

Acute inflammation: vasodilation and increased permeability produce exudate; leukocyte margination is selectin-mediated, firm adhesion is integrin/ICAM-dependent, and transmigration occurs via diapedesis.

Granulomas consist of epithelioid macrophages with or without giant cells and a lymphocyte rim; caseation suggests tuberculosis, while noncaseating granulomas occur in sarcoidosis and Crohn disease.

Primary intention healing occurs in clean apposed wounds; secondary intention involves larger defects, more granulation tissue, wound contraction, and a larger scar.

TGF-beta stimulates fibroblast proliferation and collagen synthesis; matrix metalloproteinases degrade extracellular matrix during remodeling.

Virchow triad: endothelial injury, stasis or turbulence, and hypercoagulability; all three promote thrombosis.

Dysplasia denotes disordered growth with cytologic atypia but intact basement membrane; carcinoma in situ has full-thickness atypia without invasion; invasion through basement membrane defines invasive carcinoma.

p53 is a tumor suppressor regulating DNA repair and apoptosis; retinoblastoma follows the two-hit hypothesis; APC loss initiates colorectal adenomas.

Myocardial infarction: light microscopy is normal for 4-12 hours, then coagulative necrosis appears; neutrophils peak at 1-3 days, macrophages at 3-7 days, granulation tissue at 1-2 weeks, and scar after about 2 months.

Nephrotic syndrome: proteinuria greater than 3.5 g/day, hypoalbuminemia, edema, and hyperlipidemia; nephritic syndrome: hematuria, hypertension, azotemia, oliguria, and proteinuria below 3.5 g/day.

Cirrhosis is diffuse fibrosis with regenerative nodules; complications include portal hypertension, varices, ascites, hepatic encephalopathy, and hepatocellular carcinoma.

COPD comprises emphysema and chronic bronchitis; emphysema shows enlarged airspaces with alveolar wall destruction, and chronic bronchitis requires productive cough for at least three months in two consecutive years.

Peptic ulcer disease is commonly associated with Helicobacter pylori or NSAIDs; duodenal ulcers are usually benign and gastric ulcers require biopsy to exclude malignancy.

Papillary thyroid carcinoma shows Orphan Annie nuclei, grooves, and psammoma bodies; follicular carcinoma is diagnosed by capsular or vascular invasion; medullary carcinoma secretes calcitonin and shows amyloid.

Breast carcinoma: DCIS is confined by basement membrane; LCIS is a risk marker; invasive ductal carcinoma is the most common invasive type and graded by tubule formation, nuclear pleomorphism, and mitoses.

Colorectal adenocarcinoma commonly follows APC, KRAS, and TP53 mutations; right-sided tumors often present with anemia, left-sided tumors with obstruction or bleeding.

Lung squamous cell carcinoma is central and may show keratin pearls; adenocarcinoma is peripheral and gland-forming; small cell carcinoma has neuroendocrine markers and is strongly smoking-related.

10% neutral buffered formalin is the standard fixative; use at least 10 times tissue volume and about 1 mm/hour penetration; overfixation increases antigen loss and hardening.

Processing: graded alcohols dehydrate, xylene clears, and paraffin at 56-60 C infiltrates; microtomy usually cuts 3-5 micron sections.

H&E: hematoxylin is basic and stains nucleic acids blue-purple; eosin is acidic and stains cytoplasm, collagen, and red cells pink.

PAS highlights glycogen, mucin, and basement membranes; trichrome stains collagen blue or green; reticulin stains black; Congo red shows apple-green birefringence in amyloid.

Ziehl-Neelsen stains acid-fast organisms red; Prussian blue stains iron blue; mucicarmine stains mucin; Gram stain differentiates bacteria by cell wall.

Frozen sections are used for intraoperative diagnosis, margin assessment, and tissue adequacy; lipids are retained, but freezing artifact can distort morphology.

Decalcification uses acid or EDTA; EDTA is slower but preserves antigenicity and morphology better than strong acid.

Quality control includes daily temperature monitoring, reagent logs, slide and block labeling, and equipment maintenance; turnaround time is a key performance indicator.

Common artifacts include formalin pigment, tissue folds, knife marks, and air bubbles; they must be distinguished from true pathology.

Bethesda Pap categories: NILM, ASC-US, LSIL, ASC-H, HSIL, AGC, and carcinoma; management depends on category, HPV status, and patient age.

Pap stain: superficial squamous cells are pink; intermediate and parabasal cells are blue-green; metaplastic cells have dense cytoplasm and distinct borders.

Pap adequacy: conventional smear requires well-visualized squamous cells and, in most women, endocervical or transformation-zone sampling; liquid-based cytology has different adequacy criteria.

HPV testing is used for ASC-US triage and co-testing; HPV16/18 positivity warrants colposcopy in many algorithms even with normal cytology.

Thyroid Bethesda: I nondiagnostic, II benign, III atypia of undetermined significance, IV follicular neoplasm, V suspicious for malignancy, VI malignant; malignancy risk rises with category.

Salivary gland FNA uses the Milan system: nondiagnostic, nonneoplastic, atypia, neoplasm, suspicious, and malignant.

Serous effusion: mesothelioma shows calretinin, WT1, and cytokeratin; adenocarcinoma shows MOC-31, Ber-EP4, and CEA; cell block improves immunocytochemistry.

Urine cytology: high-grade urothelial carcinoma shows cohesive clusters with high nuclear-to-cytoplasmic ratio and hyperchromasia; Paris system categories include atypical and suspicious.

Rapid on-site evaluation assesses specimen adequacy for FNA and core biopsies; it reduces nondiagnostic rates by guiding additional passes.

Immunohistochemistry requires positive and negative controls; antigen retrieval unmasks epitopes, and fixation time affects staining intensity.

Cytokeratin supports epithelial origin; vimentin supports mesenchymal; CD45 supports lymphoid; S100 supports melanocytic or neural; chromogranin and synaptophysin support neuroendocrine.

ER and PR are hormone receptors predictive of endocrine response in breast cancer; HER2 IHC 3+ is positive, 2+ equivocal requiring ISH, and 0/1+ negative.

Ki-67 is a proliferation marker; its index varies with tumor type and should be interpreted with morphology and validated cutoffs.

Mismatch repair proteins MLH1, PMS2, MSH2, and MSH6 are assessed by IHC; paired loss patterns help identify Lynch syndrome and guide BRAF or methylation testing.

PD-L1 scoring uses tumor proportion score or combined positive score depending on tumor type and assay; cutoff thresholds are drug- and indication-specific.

FISH detects amplifications and translocations; HER2 ISH is positive when ratio is 2.0 or greater or average HER2 copies are 6.0 or greater.

PCR and Sanger sequencing detect hotspot mutations; next-generation sequencing panels assess many genes and require adequate tumor cellularity and quality metrics.

Liquid biopsy analyzes circulating tumor DNA; it can detect resistance mutations but has lower sensitivity than tissue testing in many settings.

CBC indices: microcytic MCV below 80, normocytic 80-100, macrocytic above 100.

Iron deficiency: low ferritin, low serum iron, high TIBC, low transferrin saturation; anemia of chronic disease: high ferritin, low iron, low TIBC.

AML shows myeloblasts with Auer rods and MPO positivity; ALL shows lymphoblasts with TdT positivity; CLL shows smudge cells with CD5 and CD23 coexpression.

CML is defined by t(9;22) BCR-ABL1; peripheral blood shows leukocytosis with left shift, basophilia, and thrombocytosis.

Hodgkin lymphoma has Reed-Sternberg cells with CD15 and CD30; non-Hodgkin lymphoma is classified by cell lineage, immunophenotype, and genetics.

Multiple myeloma shows clonal plasma cells, CD138 positivity, rouleaux, and a monoclonal M spike; CRAB features include hypercalcemia, renal failure, anemia, and bone lesions.

ABO compatibility: group O red cells are universal for red cell transfusion; group AB plasma is universal for plasma; crossmatching prevents major incompatibility.

Acute hemolytic transfusion reaction causes fever, flank pain, hemoglobinuria, and DIC; febrile nonhemolytic reaction is common and usually benign.

PT/INR assesses extrinsic and common pathway; aPTT assesses intrinsic and common pathway; DIC shows prolonged PT and aPTT, low fibrinogen, and elevated D-dimer.

Clinical autopsies require consent and clarify cause of death, disease extent, and quality of care; medicolegal autopsies are ordered by legal authority.

Postmortem changes include algor mortis, livor mortis, rigor mortis, and putrefaction; their rates vary with temperature, body habitus, and circumstances.

Cause is the disease or injury that produced death; mechanism is the physiologic derangement; manner is natural, accident, suicide, homicide, or undetermined.

Sudden cardiac death commonly results from coronary atherosclerosis, acute plaque change, or arrhythmia; cardiomyopathy and conduction abnormalities are other causes.

Gunshot entrance wounds show a marginal abrasion, soot, and tattooing at close range; exit wounds are often larger, irregular, and lack soot.

Stab wounds are deeper than long; incised wounds are longer than deep; defense wounds occur on forearms and hands.

Asphyxia may show petechiae, congestion, and edema; ligature marks, drowning, and smothering require correlation with scene and toxicology.

Postmortem toxicology uses peripheral blood, vitreous humor, urine, and liver; postmortem redistribution can elevate central blood drug levels.

Sudden infant death syndrome is a diagnosis of exclusion; abusive head trauma may show retinal hemorrhages, subdural hematoma, and encephalopathy.

Quality assurance covers preanalytic, analytic, and postanalytic phases; errors are most frequent in preanalytic steps such as collection, labeling, and transport.

Sensitivity = TP/(TP+FN); specificity = TN/(TN+FP); PPV = TP/(TP+FP); NPV = TN/(TN+FN).

PPV and NPV depend on prevalence; sensitivity and specificity do not depend on prevalence in the tested population.

Accuracy is closeness to truth; precision is reproducibility; bias is systematic error, while random error reduces precision.

Westgard rules use control measurements; 1-3s indicates one control beyond three standard deviations, and 2-2s indicates two consecutive controls beyond two standard deviations.

Proficiency testing compares laboratory results with peer groups; accreditation programs such as CAP and CLIA assess compliance with quality standards.

Lean methods reduce waste; Six Sigma targets fewer than 3.4 defects per million opportunities.

Randomized controlled trials reduce confounding; cohort studies estimate incidence and relative risk; case-control studies estimate odds ratios.

A p-value is the probability of observed or more extreme data under the null hypothesis; it is not the probability that the null hypothesis is true.