Vasculitis - Diagnosis and Workup Overview
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Vasculitis - Diagnosis and Workup Overview

Classified by size and type of blood vessel involved, e.g., large vessels (aorta and its branches) vs. medium-sized vessels (main visceral arteries = named) vs. small vessels (vessels without names such arterioles, capillaries, venules)

STEP 1 – SUSPECT VASCULITIS

No “typical” presentation but consider in constitutionally ill patient with evidence of multisystem organ involvement and evidence of inflammation.

 • LARGE vessel: aorta/branches, e.g., external carotid, temporal, ophthalmic → limb claudication, bruits, asymmetric BP, absent pulses, HA, visual loss

 • MEDIUM vessel: renal/hepatic/mesenteric arteries, etc. → cutaneous nodules, “punched out” ulcers, livedo racemosa, digital gangrene, mononeuritis multiplex (e.g., foot/wrist drop), renovascular HTN

 • SMALL vessel: vessels of skin, small airways, glomeruli → palpable purpura, urticaria, glomerulonephritis, alveolar hemorrhage, scleritis

General Testing:

 • Inflammation? → CBC w/ diff (ACD, thrombocytosis, neutrophilia, eosinophilia), ESR, CRP

 • Organ involvement? → BMP, LFTs, CPK, stool guaiac, CXR, brain MRI (if neurologic symptoms), CT chest, CTA (if GI/claudication)

Presentation-specific Testing (i.e., small-vessel s/s):

 • Immune complex formation? → complement levels (C3, C4, consider CH50), ANA, RF/Cryoglobulins

     o ANA/RF are NOT positive in 10 vasculitis; +RF could suggest cryoglobulinemia or endocarditis (in addition to RA)

     o C3/C4 ↓ in cryoglobulinemia, SLE, and 25% of PAN; normal complement levels in all other vasculitides (rarely low in HSP)

 • ANCA-associated? → send ANCA for IIF; will reflex to MPO (p-ANCA) and PR3 (c-ANCA) antibody ELISA if positive

STEP 2 – RULE OUT MIMICS

Ddx: Infections (SBE, HIV, HBV, HCV, EBV, Neisseria, Syphilis), malignancies (leukemia, lymphoma, myeloma, MDS, solid tumors), IgG4-Related Disease (IgG4-RD, NEJM 2012;366:539, Mod Pathol 2012;25:1181), cocaine / levamisole, other drug-induced vasculitides, hypercoagulable states (APLAS, TTP)

 • If skin necrosis of lower extremities → consider cholesterol emboli or calciphylaxis

 • If renal artery, internal carotid artery, vertebral artery involvement → consider fibromuscular dysplasia

Tests: BCx, HBV, HCV, HIV, SPEP/UPEP/SFL/UFL, tox screen, consider IgG4

STEP 3 – CONFIRM DIAGNOSIS

 • Tissue biopsy: typically required to secure diagnosis

 • Angiography: particularly if tissue biopsy is unfeasible



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