Collagen vascular disease.

The iatrogenic L-tryptophan-induced eosinophilia-myalgia syndrome, often considered to be a "new" disease, has proven to be a remarkable mimic of the classic sclerosing rheumatologic disorders. Although subacute cutaneous lupus erythematosus remains a clinically defined entity, supportive histologic and immunopathologic findings have recently been proposed. Rheumatoid neutrophilic dermatitis needs to be added to our usual differential diagnosis of a neutrophilic dermatosis without leukocytoclastic vasculitis. The antiphospholipid syndrome is associated with noninflammatory vascular thrombosis and often has recognizable cutaneous findings. Finally, ANCA are a valuable adjunct in the systemic evaluation of patients with vasculitis syndromes and suggest a common pathogenesis for several of the systemic vasculitides.