Blue rubber-bleb nevus syndrome with Masson's vegetant intravascular hemangioendothelioma.

A 14-year-old Japanese male showed numerous small cutaneous hemangiomas and severe anemia produced by internal hemorrhages from intestinal hemangiomas. Histological studies revealed ectatic vessels lined by a single layer of endothelial cells. Six hemangiomas, with fibrous walls of variable thickness, showed characteristics of vegetant intravascular hemangioendothelioma (Masson) in an organizing thrombus. Electron microscopy confirmed that the dilated cavities, were lined by a layer of flattened endothelial cells, surrounded by a few pericytes and/or smooth muscle cells. No appreciable abnormalities were found in the blood vessels located in the clinically normal skin. A few amyloid deposits in the subepidermal connective tissue were also observed.