Eosinophilic cellulitis: histologic features in a cutaneous mastocytoma.

A cutaneous mastocytoma with associated histologic features of eosinophilic cellulitis is reported. The tumor occurred as a small, asymptomatic lesion on the left thigh of a 4-year-old boy. Microscopically, an accumulation of mast cells, microgranulomas, eosinophils and 'flame figures' was present. A pathogenesis involving mast cell degranulation, eosinophil chemotactic factors and eosinophil major basic protein is discussed.