Angiolymphoid hyperplasia with eosinophilia of the skin. Light microscopic and ultrastructural study of 4 cases.

A clinical, light and electron microscopic study of four patients with angiolymphoid hyperplasia with eosinophilia of the skin is presented. Light-microscopically, the lesions were characterized by the small size and superficial location, the proliferation of mostly delicate vessels with prominent endothelial hyperplasia and cellular areas without distinct vessel structures, but with infiltrates of eosinophilic leukocytes, lymphocytes and plasma cells. Ultrastructurally, a marked proliferation of both endothelial cells and pericytes could be demonstrated and the solid cellular areas were shown to be composed of solid vascular buds. A multi-layered basal lamina was enclosing pericytes and external surfaces of endothelial cells. The differential diagnosis is discussed and it is emphasized that this lesion may be misinterpreted as angiosarcoma.