Abstract
We treated a 70-year-old man with malignant hemangioendothelioma on the left temporal area. Histopathologically, tumor cells were observed throughout the dermis. Many of the tumor cells seemed to be immature mesenchymal cells, but formed slit-like lumens, in some areas. Peroxidase-antiperoxidase staining using an antihemophilic factor antigen revealed a positive substance in some tumor cells. Electron-microscopically, the tumor cells had Weibel-Palade granules in the cytoplasm.
