Systemic Pathology - Organ System Review

🟢 Lite — Quick Review (1h–1d)

Rapid summary for last-minute revision before your exam.

Systemic Pathology — Key Facts for FMGE Core concept: Major organ systems have characteristic pathological responses and disease patterns that recur across different diseases High-yield point: Each organ has its own pattern of injury response - heart undergoes coagulative necrosis, brain undergoes liquefactive necrosis ⚡ Exam tip: Connecting pathophysiology to clinical findings and understanding why specific organs develop specific lesions is key to FMGE success

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🟡 Standard — Regular Study (2d–2mo)

Standard content for students with a few days to months.

Systemic Pathology — FMGE Study Guide

Cardiovascular Pathology

Atherosclerosis

• Intimal atherosclerosis: Lipid-laden plaques in aorta, coronary arteries, cerebral arteries
• Risk factors: Hypertension, smoking, diabetes, hyperlipidemia, family history
• Complications: Ischemic heart disease, stroke, peripheral vascular disease
• Morphology: Foam cells, fibrous cap, necrotic lipid core, calcification

Ischemic Heart Disease

• Angina pectoris: Stable (exertional), unstable (crescendo), variant (Prinzmetal - coronary spasm)
• Myocardial infarction:
  • Transmural (STEMI): Full thickness necrosis; Q wave on ECG
  • Subendocardial (NSTEMI): Inner half of myocardium
• Evolution of MI: 0-4h (no change) → 4-12h (early coagulative necrosis, wavy fibers) → 12-24h (early neutrophil infiltration) → 1-3 days (macrophages, early granulation) → 1-3 weeks (granulation tissue) → months (fibrosis, scar)
• Complications: Arrhythmias (most common cause of death within first hour), cardiogenic shock, mural thrombus → embolism, papillary muscle rupture (mitral regurgitation), ventricular septal rupture, cardiac tamponade (free wall rupture), CHF, Dressler syndrome (autoimmune pericarditis)

Hypertension

• Benign: Essential hypertension - small vessel arteriolosclerosis (hyaline)
• Malignant: Accelerated - fibrinoid necrosis, onion-skinning, malignant nephrosclerosis
• Effects: Left ventricular hypertrophy → heart failure, Hypertensive nephrosclerosis → renal failure, Charcot-Bouchard microaneurysms → cerebral hemorrhage

Cardiomyopathy

• Dilated: Most common; heart enlarged, flabby; systolic dysfunction; myocarditis, alcoholism, genetic
• Hypertrophic: Asymmetric septal hypertrophy; autosomal dominant; systolic anterior motion (SAM) of mitral valve; sudden death in young athletes
• Restrictive: Infiltrative (amyloidosis, sarcoidosis), endomyocardial fibrosis

Valvular Heart Disease

• Mitral stenosis: Most commonly rheumatic; left atrial enlargement, pulmonary congestion, atrial fibrillation
• Mitral regurgitation: Volume overload, cardiomegaly, pulmonary edema
• Aortic stenosis: Calcific degeneration (elderly), congenital bicuspid aortic valve; sync_pe, angina, heart failure; left ventricular hypertrophy
• Aortic regurgitation: Wide pulse pressure, Corrigan pulse (water hammer), De Musset sign, Austin Flint murmur
• Infective endocarditis: Vegetations on heart valves; acute (S. aureus - aggressive) vs subacute (Strep viridans - more indolent); Duke criteria

Aneurysms

• True aneurysm: All three layers intact; atherosclerotic (abdominal aorta), syphilitic (thoracic aorta)
• False aneurysm (pseudoaneurysm): Hematoma with fibrous capsule; trauma, percutaneous procedures
• Dissecting aneurysm: Blood in media - Classically hypertension; Stanford Type A (ascending aorta) and Type B (descending aorta); acute aortic regurgitation, cardiac tamponade, branch vessel occlusion

Pulmonary Pathology

Pneumonia

• Lobar pneumonia (Streptococcus pneumoniae): Stages - congestion (day 1), red hepatization (day 2-3), gray hepatization (day 4-8), resolution (day 9+)
• Bronchopneumonia (Staph, Strep, H. influenzae): Patchy consolidation around bronchi
• Interstitial pneumonia (viral - influenza, COVID-19): Diffuse alveolar damage, bilateral involvement

COPD and Emphysema

• Chronic bronchitis: Productive cough >3 months/year for >2 consecutive years; Reid index >50%
• Emphysema: Destruction of alveolar walls; centriacinar (smoking) - upper lobes; panacinar (alpha-1 antitrypsin deficiency) - lower lobes
• Pathophysiology: Loss of elastic recoil, airflow obstruction, air trapping, hyperinflation

Asthma

• Type I hypersensitivity; bronchial smooth muscle hypertrophy, eosinophilic infiltrate, mucous gland hyperplasia
• Atopic (extrinsic) and Intrinsic (non-atopic)
• Status asthmaticus: Severe, refractory bronchospasm

Lung Cancer

• Squamous cell carcinoma: Central, keratin pearls, associated with smoking
• Adenocarcinoma: Peripheral (most common overall in non-smokers), glandular differentiation, mucin
• Small cell carcinoma: Central, neuroendocrine, oat cells, paraneoplastic syndromes (SIADH, ectopic ACTH)
• Large cell carcinoma: Poorly differentiated, giant cells
• Metastasis: Brain, bone, liver, adrenal

Tuberculosis

• Primary TB: Ghon complex, lower/middle lobe
• Secondary TB: Apical cavitary lesions (reactivation)
• Caseating granulomas: Central caseous necrosis, Langhans giant cells
• Miliary TB: Thousands of tiny tubercles throughout lungs and other organs

GI Pathology

Peptic Ulcer Disease

• Gastric ulcer: Greater curvature; risk of malignancy
• Duodenal ulcer: Lesser curvature of pylorus; associated with H. pylori; pain relieved by eating
• Complications: Hemorrhage, perforation, penetration, pyloric obstruction

Gastritis

• Acute gastritis: Erosions, alcohol, NSAIDs, stress (Curling ulcer - burns, Cushing ulcer - CNS injury)
• Chronic gastritis: Type A (fundal - autoimmune, pernicious anemia), Type B (antral - H. pylori, most common)

Inflammatory Bowel Disease

• Crohn disease: Transmural inflammation, skip lesions, non-caseating granulomas, cobblestone mucosa, creeping fat, string sign on barium, perianal disease
• Ulcerative colitis: Mucosal inflammation, continuous lesions starting from rectum, crypt abscesses, pseudopolyps, toxic megacolon; increased colon cancer risk

Colorectal Carcinoma

• Most common GI cancer; adenocarcinoma
• Adenoma-carcinoma sequence: APC mutation → K-ras → DCC → p53
• Left colon: Narrowing, constricting (cauliflower-like)
• Right colon: Annular, apple-core appearance
• Elevated CEA (carcinoembryonic antigen)

Hepatitis

• Viral hepatitis patterns:
  • Acute viral hepatitis: Spotty necrosis, Councilman bodies (apoptotic bodies), portal inflammation
  • Chronic hepatitis: Portal tract expansion, interface hepatitis, cirrhosis
  • Fulminant hepatitis: Massive necrosis, hepatic encephalopathy
• Alcoholic hepatitis: Mallory bodies (intracytoplasmic eosinophilic inclusions), neutrophilic infiltrate, fatty change
• Cirrhosis: Micronodular (alcohol, biliary) vs macronodular (viral, autoimmune)

Renal Pathology

Glomerulonephritis

Nephritic syndrome (hematuria, proteinuria <3.5g/day, hypertension, edema, oliguria):

• Acute proliferative GN (post-streptococcal): “Looped” or “lumpy bumpy” immunofluorescence; subepithelial humps
• IgA nephropathy (Berger disease): Episodic gross hematuria following URI; mesangial IgA deposits
• Rapidly progressive (Crescentic) GN: Crescent formation (proliferation of parietal cells and macrophages in Bowman’s space); poor prognosis

Nephrotic syndrome (proteinuria >3.5g/day, hypoalbuminemia, edema, hyperlipidemia):

• Minimal change disease: Children; foot process effacement on EM; responds to steroids
• Focal segmental glomerulosclerosis (FSGS): HIV-associated; heroin-associated; primary
• Membranous nephropathy: “Spike and dome” appearance; adults; may be secondary to malignancy, hepatitis B, SLE, drugs
• Amyloidosis: Kidney involvement → nephrotic syndrome

Tubulointerstitial Disease

• Acute tubular necrosis (ATN): Ischemic (shock) or nephrotoxic (aminoglycosides, contrast dye)
• Acute pyelonephritis: Neutrophilic infiltration of interstitium and tubules; WBC casts
• Chronic pyelonephritis: Tubular atrophy, interstitial fibrosis, Thyroidization of tubules; associated with vesicoureteral reflux or obstruction

Renal Cell Carcinoma

• Clear cell carcinoma: Most common; “Clear cells” due to glycogen and lipid; associated with VHL gene mutation
• Papillary carcinoma: Multicentric, bilateral
• Wilms tumor (nephroblastoma): Children; triphasic (blastema, stromal, epithelial elements)

Nervous System Pathology

Stroke

• Ischemic stroke (87%): Thrombotic (atherosclerotic large vessel) or embolic (cardioembolic - AF, mural thrombus)
• Hemorrhagic stroke (13%): Hypertension → Charcot-Bouchard microaneurysm rupture; amyloid angiopathy (elderly)
• Liquefactive necrosis: Brain tissue undergoes enzymatic digestion → cystic cavity

CNS Tumors

• Gliomas: Astrocytoma (most common primary brain tumor), oligodendroglioma (fried egg cells), ependymoma
• Meningioma: Arachnoid cells; dural attachment; psammoma bodies; benign but can recur
• Medulloblastoma: Children; small round blue cells; cerebellar
• Metastatic: Most common brain tumors; lung, breast, melanoma, colon, kidney

Neurodegenerative Diseases

• Alzheimer disease: Neuritic plaques (Aβ), neurofibrillary tangles (tau), cortical atrophy; ApoE4 associated
• Parkinson disease: Loss of dopaminergic neurons in substantia nigra; Lewy bodies (α-synuclein); resting tremor, bradykinesia, rigidity, postural instability
• Huntington disease: Caudate atrophy; CAG repeats in huntingtin gene
• Multiple sclerosis: Demyelination; periventricular white matter plaques; relapsing-remitting course

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