Approach to cutaneous vasculitides with special emphasis on small vessel vasculitis: histopathology and direct immunofluorescence.

PURPOSE OF REVIEW: The present review will focus on recent publications in cutaneous vasculitides. RECENT
FINDINGS: Some histopathological and clinical features, such as papillary dermal edema, perivascular C3 deposition, clinically evident edema, and lesions above the waist, may point out renal or gastrointestinal involvement in Henoch-Schönlein purpura (HSP). HSP associated with familial Mediterranean fever differs from typical isolated HSP by showing no deposits of IgA, much younger age, and location of the lesions on the face or the trunk. Single-organ cutaneous small vessel vasculitis is a more restricted entity than hypersensitivity vasculitis and HSP. Because cutaneous polyarteritis nodosa and macular lymphocytic arteritis share some clinicopathologic features, the question is raised whether they are not two different entities. Several histopathological features defining IgG4-related disease are found in granuloma faciale and erythema elevatum diutinum, two localized chronic cutaneous vasculitis; however, in a recent series no diagnostic criteria for IgG4-related disease was detected in them.
SUMMARY: When a patient presents with skin lesions, in which necrotizing or leukocytoclastic vascuitis is confirmed histologically, irrespective of the size of the affected vessel, the possibility of systemic vasculitis, an infection, medication, or a systemic disease such as systemic lupus erythematosus must be searched before reaching definitive diagnosis.