The Tip of the Iceberg: A Gastrointestinal Stromal Tumor in a Young Adult

Abstract

Gastrointestinal stromal tumors (GIST) are rare tumors that constitute approximately 1% of primary gastrointestinal tumors, usually diagnosed in patients above 50 years of age. We present a case of GIST diagnosed in a young adult with interesting endoscopic and radiographic imaging. A 26-year-old Hispanic man was hospitalized for five days of fatigue and headache. Review of symptoms was positive for a three month history of progressive fatigue and intermittent black colored stool. Medical history was unremarkable, social history was negative for alcohol, tobacco or other drug use and patient endorsed only occasional use of non-steroidal anti-inflammatory drugs. Family history was negative for GI malignancies. On admission, exam revealed tacycardia, but the patient was otherwise hemodynamically stable. He was found to have a severe microcytic anemia, with hemoglobin of 3.2 mg/dl and MCV of 74. The patient responded to 3 units of packed red blood cells and underwent urgent EGD, revealing a 2.5 cm round mass with an ulcerated surface, on the greater curvature toward the anterior wall (A), the lesion was biopsied. On abdominal CT, a 6.6 cm lobulated, exophytic, hypervascular and necrotic mass was demonstrated, arising from the proximal body of the stomach (B). A laparoscopic partial gastrectomy was performed and surgical specimen consisted of a 6.7x6.2x4.6 cm, soft-tissue tumor. Pathology revealed a mixed spindle and epithelioid tumor subtype, with a mitotic rate of 11/50 per high power field (C), consistent with a diagnosis of GIST, stage IIIa. The patient has been doing well under active surveillance with oncology and was started on Imatinib as adjuvant therapy. GIST tumors predominantly occur in patients over the age of 50 and are uncommonly seen before 40 years of age. In fact, the reported incidence in adults between ages 20-29 years is 0.06/million/year. Our case demonstrates the unique features of a GIST tumor in a young adult who presented with fatigue and found to have severe anemia from a chronic GI bleed, which led to the diagnosis. Abdominal pain with or without GI bleeding is the most common presenting symptom, however the unique structure of the GIST, as exemplified by our case, enables significant tumor growth before symptoms ensue. Sometimes, the lesions detected by endoscopy are just the “tip of the iceberg”, therefore imaging is pertinent for staging and management. Tumor size and histology both effect treatment and prognosis.Figure. 2: 5 cm round mass with an ulcerated surface, on the greater curvature toward the anterior wall of the stomach, viewed only during retroflexion in the body.Figure: Cross sectional view of the stomach on abdominal CT with contrast, demonstrating a well-circumscribed, exophytic mass arising from the proximal body of the stomach and measuring 6.4 x 6.6 x 6.6 cm.Figure: Above: Histologic section demonstrating submucosal tumor mass composed of nests, fascicles and sheets of short spindle cells and epithelioid cells. (H & E; x 4) Below: Histologic section of the tumor cells with mitosis (red arrow). (H & E; x20).