General Pathology and Pathophysiology
Core concepts
Focus on the mechanisms that link aetiology to morphology and to clinical consequence: cell injury and the reversible/irreversible threshold (ATP depletion, calcium influx, membrane failure), the distinction between necrosis subtypes (coagulative, liquefactive, caseous, fat, fibrinoid) and apoptosis, and the pathways of acute versus chronic inflammation. Understand granuloma formation (caseating vs non-caseating), wound healing phases, and the sequence of thrombosis, embolism, infarction and organisation. Neoplasia requires fluency in dysplasia versus carcinoma in situ versus invasion, grading versus staging, tumour suppressor versus oncogene logic, and the common paraneoplastic and metastatic routes.
Traps in questions
Questions often test the first or most specific change rather than the endpoint. For example, the earliest reversible ultrastructural change in ischaemia is mitochondrial swelling and ribosomal detachment, not membrane rupture. Distinguish transudate from exudate by protein and cellular content and by specific gravity. Do not confuse metaplasia (reversible change of one mature cell type to another) with dysplasia (disordered maturation with atypia). Watch for questions pairing a disease with its classic histological pattern: psammoma bodies (papillary thyroid carcinoma, papillary serous ovarian tumours), Reed-Sternberg cells, Aschoff bodies, and Langhans giant cells.
Worked rule of thumb
When asked to classify a vascular lesion, use the vessel size and wall composition as the anchor: fibrinoid necrosis with necrotising inflammation in medium vessels suggests polyarteritis nodosa; granulomatous inflammation of the aortic media with vasa vasorum involvement suggests giant cell arteritis; intimal hyperplasia with a "onion-skin" pattern in small arteries suggests hypertensive or scleroderma renal change. Anchor the answer in vessel calibre first, then overlay inflammation type.
Exam strategy
Build a mental table mapping each pathological process to its prototypical organ example and the single most characteristic microscopic feature.