| Disease | Epidemiology & Risk | Pathology & Mechanism | Clinical Presentation | Step 1 High-Yield Labs/Rx |
|---|---|---|---|---|
| Giant Cell (Temporal) Arteritis | Elderly females (>50). Associated with Polymyalgia Rheumatica. | Granulomatous inflammation of branches of the carotid artery. | Unilateral headache, jaw claudication, tenderness over temporal artery. Vision loss (ophthalmic artery occlusion). | ↑ ESR/CRP. Rx: High-dose corticosteroids immediately. Biopsy: Intimal fibrosis, giant cells. |
| Takayasu Arteritis | Asian females < 40 years old. | Granulomatous thickening and narrowing of the aortic arch. | "Pulseless disease" (weak upper extremity pulses), fever, night sweats, skin nodules. | ↑ ESR. Rx: Corticosteroids. |
| Disease | Epidemiology & Risk | Pathology & Mechanism | Clinical Presentation | Step 1 High-Yield Labs/Rx |
|---|---|---|---|---|
| Polyarteritis Nodosa (PAN) | Young adults. Strong association with Hepatitis B (HBsAg+). | Transmural inflammation with fibrinoid necrosis. Lesions of *different ages* ("string of pearls"). | Fever, weight loss, GI pain, melena. Renal HTN. Spares the lungs. | Negative ANCA. Angiogram: microaneurysms. Rx: Corticosteroids, cyclophosphamide. |
| Kawasaki Disease | Asian children < 4 years old. | Necrotizing vasculitis with mucocutaneous lymph node syndrome. | CRASH and Burn: Conjunctivitis, Rash, Adenopathy, Strawberry tongue, Hand/foot changes, Fever > 5 days. | Complication: Coronary artery aneurysms. Rx: IVIG + Aspirin. |
| Buerger Disease | Heavy smokers, males < 40. | Segmental thrombosing vasculitis extending into veins/nerves. | Intermittent claudication, Raynaud. Gangrene of digits. | Rx: Smoking cessation. |
| Disease | Epidemiology & Risk | Pathology & Mechanism | Clinical Presentation | Step 1 High-Yield Labs/Rx |
|---|---|---|---|---|
| Granulomatosis with Polyangiitis (Wegener) | Middle-aged males. | Triad: Necrotizing vasculitis, Granulomas (lung/airway), Glomerulonephritis. | Nasopharyngeal (perforated septum), Hemoptysis, Hematuria (RPGN). | c-ANCA (PR3-ANCA). CXR: Nodules. Rx: Cyclophosphamide. |
| Microscopic Polyangiitis (MPA) | No specific gender. | Necrotizing vasculitis (no granulomas). | Similar to Wegener but no nasopharyngeal and no granulomas. Palpable purpura. | p-ANCA (MPO-ANCA). |
| Churg-Strauss | History of atopy/asthma. | Granulomatous, necrotizing vasculitis with eosinophilia. | Asthma, sinusitis, neuropathy (wrist drop). | p-ANCA (MPO-ANCA). IgE elevated, Eosinophilia. |
| Henoch-Schönlein Purpura | Children, post-URI. | Vasculitis 2° to IgA deposition. | Triad: Palpable purpura (buttocks), Arthralgias, GI pain. | Renal Biopsy: Mesangial IgA. Rx: Supportive. |
| Disease | LM/IF/EM Findings | Clinical / Associations |
|---|---|---|
| PSGN | LM: Hypercellular. IF: "Starry sky" (Lumpy-bumpy) IgG/C3. EM: Subepithelial humps. | Children, 2-4 wks post-Strep. Cola-colored urine. ↓ C3. |
| RPGN | LM: Crescents (fibrin/macrophages). | Rapid deterioration. Goodpasture (Linear IF), Wegener (Pauci-immune). |
| DPGN | LM: "Wire looping". EM: Subendothelial deposits. | SLE (Lupus Nephritis). |
| IgA Nephropathy | IF: IgA deposits in mesangium. | Episodic hematuria concurrent with URI/GI infection. |
| Alport Syndrome | EM: "Basket-weave" GBM. | X-linked. Mutation in Type IV collagen. Deafness + Eye problems. |
| MPGN | LM: "Tram-track". Type I: Hep B/C. Type II: C3 Nephritic Factor. | Mixed Nephritic/Nephrotic. |
| Disease | LM/IF/EM Findings | Clinical / Associations |
|---|---|---|
| Minimal Change Disease | EM: Effacement of foot processes. | Children. Excellent response to steroids. |
| FSGS | LM: Segmental sclerosis. EM: Effacement of foot processes. | African Americans, HIV, Heroin, Sickle Cell. |
| Membranous Nephropathy | EM: "Spike and dome" (subepithelial). Anti-PLA2R. | Caucasian adults. Hep B/C, SLE, Tumors. |
| Diabetic Nephropathy | LM: Kimmelstiel-Wilson nodules. | Hyperfiltration injury. Rx: ACE inhibitors. |
| Amyloidosis | Congo Red: Apple-Green Birefringence. | Associated with Multiple Myeloma or Chronic Inflammation. |