GASTROINTESTINAL STROMAL TUMOR PRESENTING AS LUNG MASS: A CASE REPORT

Abstract

PURPOSE: Gastrointestinal stromal tumors (GISTs) are rare neoplasms of the gastrointestinal tract commonly seen in middle-aged and elderly adults with the most common location in the stomach and small intestine. We present a case of a 20-year-old Filipino male with a 2-week history of exertional dyspnea which on work up showed a left pulmonary mass consistent with a high grade gastrointestinal stromal tumor with no evidence of intra-abdominal GIST. METHODS: Immunohistochemistry revealed spindle cells positive for CD 117, DOG-1, and CD 56, negative for CK, TTF-1, SMA, desmin, S-100, and CD34. He underwent attempted video-assisted thoracoscopic surgery (VATS), open thoracotomy, lung mass biopsy, tumor debulking and decortication. RESULTS: The patient began treatment with oral imatinib mesylate (Gleevec) at a dose of 400mg/day but was refractory after 3 months of treatment. The patient had pulmonary infection and evidence of tumor progression at that time. He then underwent radiotherapy and a second line pazopanib 400mg/day was started. Partial response was achieved after two to three months. The patient is currently stable and with good functional capacity. CONCLUSIONS: This paper presents a rare case of a lung mass that turned out to be a gastrointestinal stromal tumor (GIST) in a 20-year old male without evidence of intra-abdominal GIST on work-up. Immunotherapy is very crucial in the diagnosis. CLINICAL IMPLICATIONS: GISTs outside the gastrointestinal tract appear to relapse more frequently. Lung GIST may have different clinical behavior and does not very well respond to first-line oral imatinib.