Cutaneous polyarteritis nodosa. Report of a case associated with Crohn's disease.

A patient had cutaneous polyarteritis nodosa associated with Crohn's disease. Immunopathologic studies disclosed evidence of circulating immune complexes as measured by C1q binding. Immunofluorescent microscopy of lesional skin showed C3 and fibrin deposition. Histamine injection of normal skin and subsequent biopsy specimens and immunofluorescent microscopy showed immune deposits. The patient was treated with cyclophosphamide and prednisone with a good clinical response, but within two years, histiocytic lymphoma developed. There is an association of cutaneous polyarteritis and Crohn's disease, and also, immunosuppressive therapy plays a role in the development of histiocytic lymphoma.