General Pathology

Cellular injury, inflammation, neoplasia and the general mechanisms that underlie every organ-system chapter.

Exam weight 12–15% · 2 QBank items · 3 flashcards

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Cell injury & death

Reversible injury: cellular swelling, ribosomal detachment; irreversible: mitochondrial vacuolisation, membrane rupture, nuclear pyknosis→karyorrhexis→karyolysis.
Coagulative necrosis everywhere except brain (liquefactive); caseous in TB; fat necrosis in pancreatitis with saponification.
Apoptosis is ATP-dependent and non-inflammatory; intrinsic pathway uses Bcl-2/Bax and cytochrome c, extrinsic uses Fas-FasL.
Red (hemorrhagic) infarcts occur in loose tissue with dual blood supply — lung, intestine, testes; pale infarcts in solid organs.

Acute inflammation is neutrophil-driven with margination, rolling (selectins), tight adhesion (integrins) and transmigration.
Chronic inflammation is macrophage and lymphocyte driven; granuloma formation requires IFN-γ and TNF-α — anti-TNF drugs reactivate TB.
Acute-phase reactants: ferritin, fibrinogen, CRP, hepcidin up; albumin and transferrin down.
Wound healing: granulation tissue by day 3–5, collagen type III replaced by type I during remodelling; vitamin C and zinc are required.

Hallmarks: evasion of apoptosis, growth signal self-sufficiency, limitless replication, angiogenesis, invasion and metastasis.
Oncogenes need one hit (RAS, MYC, HER2); tumour suppressors need two (RB, TP53, APC) per Knudson.
Tumour markers: AFP hepatocellular and yolk sac, CA-125 ovarian, CEA colorectal, PSA prostate, β-hCG gestational trophoblastic.
Paraneoplastic: small-cell lung → SIADH, ACTH, Lambert-Eaton; squamous cell lung and renal cell → PTHrP hypercalcemia.

Virchow triad: stasis, endothelial injury, hypercoagulability.
Transudate (low protein, low LDH) from heart failure or cirrhosis; exudate (high protein/LDH per Light criteria) from infection or malignancy.
Shock types: hypovolemic and cardiogenic have low cardiac output with cold extremities; distributive has high output with warm extremities.
Amyloidosis: apple-green birefringence with Congo red; AL from plasma cell dyscrasia, AA from chronic inflammation.