Multiple gastrointestinal stromal tumors of the ileum and neurofibromatosis type 1.

Type 1 neurofibromatosis, also known as von Recklinghausen disease, is one of the most common genetic disorders. Gastrointestinal associations have been well described in these patients, but the true incidence of gastrointestinal tumors and the proportion of these becoming clinically significant are not known. The most common gastrointestinal tumors are stromal tumors, most of which are located in the stomach and jejunum. We discuss the case of a female patient with neurofibromatosis whose initial diagnosis was an ovarian mass. During surgery the diagnosis of an intestinal stromal tumor was made. Operative findings were a multilobulated tumor arising from the ileal wall 50 cm from the ileocecal valve. The tumor did not originate from the nervous myenteric plexus or muscular layer of the small bowel wall; it originated from within the stromal cells of the intestinal wall. Mitotic count showed 3 mitoses per 10 high-power fields. Immunohistochemical stains of the tumor showed positive staining for CD117 and CD34 and negative staining for S100, alpha-smooth muscle actin, and desmin. The intestinal myenteric plexus showed positive staining for chromegranin A and S100. The histologic characteristics of this patient's tumor are compatible with an undifferentiated stromal tumor of nonneural or nonmuscular origin.