Hypoglycemia induced by secretion of high molecular weight insulin-like growth factor-II from a malignant solitary fibrous tumor of the pleura.

A 49-year-old woman with a malignant solitary fibrous tumor of the pleura presented with hypoglycemia. Most of the serum insulin-like growth factor II (IGF-II) existed as high molecular weight IGF-II. Furthermore, there were larger amounts of high molecular weight IGF-II found in the tumor cystic fluid than in the serum. After surgical resection of the tumor, high molecular weight IGF-II was not detected in the serum and the hypoglycemia resolved. Immunohistochemically, IGF-II was localized in the so-called Golgi area of the tumor cell. These findings suggest that hypoglycemia in this patient was caused by the high molecular weight IGF-II produced by the tumor.