Solitary fibrous tumor of the pleura. An immunohistochemical, electron microscopic and tissue culture study of a tumor producing insulin-like growth factor I in a patient with hypoglycemia

We report a patient with recurrent hypoglycemia most likely caused by a solitary fibrous tumor of the pleura. After removal of the tumor, hypoglycemia resolved. The bland histologic picture of this tumor is emphasized. Electron microscopic and immunohistochemical observations support its non-mesothelial derivation. In vitro studies demonstrated that the tumor tissue produced insulin-like growth factor I (IGF-I), and its role as the cause of hypoglycemia is discussed.