Intrascieral Schwannoma

Abstract

Under light microscopy, the tumor was considered to be a mixed Schwannoma, fibrous histiocytoma or an atypical malignant melanoma of the choroid infiltrating the sclera and episcleral tissues. Although the preservation of the tissue studied by transmission electron microscopy was inadequate for a definitive diagnosis, this part of the investigation excluded the possibilities that this spindle cell tumor was a malignant melanoma or a tumor derived from the smooth muscle. The fine structure of the tumor cells and the extracellular tissue was similar in appearance to that described in published accounts of the fine structure of human Schwannomas in various anatomical sites, and the most notable feature was the presence of basement membrane material around the extended cytoplasmic processes.