Today we discussed leukocytoclastic vasculitis, and one of its causes, polyarteritis nodosa (although LCV is not the most typical skin involvement; livedo reticularis is more common). A few points:
Leukocytoclastic vasculitis = palpable purpura, usually lower extremity.
This is not a diagnosis; it is associated with many potential etiologies
Differential diagnosis of this presentation: A useful mnemonic is VASCULITIS (courtesy of Dr. Scott Walsh)
V- viral (Hep C, Hep B, HIV)
A- autoimmune (SLE, RA, Sjogren's, Henoch-Schonlein purpura)
S- staph, strep infections
C- cryoglobulinemia (e.g. from Hep C, RA)
U- ulcerative colitis, crohn's
L- lymphoproliferative disorders (esp. hairy cell leukemia)
I- infection- endocarditis, meningococcemia
T- thiazides, NSAIDS
I- immune complex (e.g. from endocarditis)
S- septra, b-lactam antibiotics
Polyarteritis nodosa
Medium or small vessel vasculitis typically presenting as multisystem disease, fever, abdominal pain, renal involvement, hypertension, and skin lesions.
The ACR criteria include weight loss skin lesions, testicular pain, myalgias, HTN, renal involvement, neuropathy, HBV infection, angiographic findings, and biopsy findings.
Hep B surface antigen is present in 15%; there is also an association with HCV, but less commonly. p-ANCA is sometimes positive, but is not a criterion.
Diagnosis is clinical, but strongly supported by tissue (usually either a nerve- usually sural nerve, skin, or kidney biopsy depending on organ involvement), or angiographic findings.
Treatment is immunosuppression (steroids +/- cytotoxic agents)
Some links:
Click here for a NEJM clinical pathological case of PAN
Click here for a previous blog post on general approach to vasculitis
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