Cutaneous polyarteritis nodosa: a clinical and histopathological study of 20 cases.

Twenty cases diagnosed as cutaneous polyarteritis nodosa (CPN) and confirmed by skin biopsy over the last 17 years were reviewed in our department. Based upon their clinical features, laboratory findings, and long-term observation of the disease course, they were divided into three groups. 1) Group 1 comprised 16 cases which were classified as the mild cutaneous form. The disease was confined to the skin with occasional involvement of peripheral nerves and skeletal muscles of the affected extremity. They generally followed a benign course. 2) Group 2 comprised 2 cases classified as the severe form. Despite severe clinical manifestations and several abnormal laboratory findings, the disease was limited to the skin, muscles, and peripheral nerves without any visceral involvement over follow-up periods of 11 years and 5 years, respectively. 3) Group 3 comprised 2 cases of the progressive form; in these the disease had begun with a cutaneous lesion and progressed to the systemic form after 19 and 18 year periods of recurrent episodes of cutaneous lesions, respectively. One died of gastrointestinal bleeding. In group 3, serum antinuclear antibodies and rheumatoid factor were positive. The autoimmune mechanism seems to play a role in this group. It is clear from the results of this study that not all patients whose vasculitic lesions are apparently limited to the skin remain in a benign course. Long-term follow-up is essential.