Sellar glomangioma.

A glomangioma (glomus tumor) arising in the pituitary region is described. The histologic and ultrastructural features were characteristic. The tumor was composed of epithelioid cells arranged in an organoid fashion around vascular channels and contained scattered mast cells. Electron microscopy revealed tumor cells that showed features of smooth muscle differentiation. Immunocytology demonstrated the presence of actin, desmin, and myoglobin within tumor cells and basement membrane antigen surrounding them; factor VIII was localized in endothelial cells and not within tumor cells. Pituitary hormones were not detected in the tumor by the immunoperoxidase technique. This is the first report of a glomangioma of the sella turcica. The gomitoli of the hypophyseal portal vessels are structures that resemble glomera found in other sites. Derivation of this tumor from gomitoli is suggested.