Skin eruptions associated with microscopic polyangiitis.

Microscopic polyangiitis (MPA) is a systemic vasculitis histologically characterized by small-vessel involvement. Antineutrophil cytoplasmic antibodies (especially anti-myeloperoxidase antibodies) (MPO-ANCA) are often positive in serum. Although the skin is affected in 20-70% of patients, the precise description has been limited. This retrospective study analyzed clinical manifestations in patients of MPA with skin eruptions. Ten patients with skin eruptions diagnosed as MPA according to Chapel Hill consensus criteria consisted of 6 men and 4 women aged from 38 to 80 years (62.1 +/- 13.3). Clinical manifestations, laboratory data, and histological findings were examined. Purpura and petechiae in 6 patients, livedo in 2 patients, and erythema in 7 patients, especially erythema on the hands and\or fingers in 4 patients, were observed. Histological findings from the eruptions in 7 patients showed perivascular lymphocyte infiltration in the upper dermis in 4 patients, and infiltration of lymphocytes and a few neutrophils around small arteries in the middle to deep dermis in 2 patients and diffuse infiltration of histiocytes and lymphocytes in the middle dermis in 1 patient. Cutaneous involvements in MPA showed a wide spectrum of clinical and histological findings.