A 47 year old African American male presented to the emergency department with intermittent, severe chest pain associated with palpitations and one episode of vomiting.. The pain started without any preceding event and persisted for approximately 30 seconds during both rest and exercise. The patient claimed to use street cocaine for the treatment of his pain. During the last few months the patient experienced a 40 pound weight loss. The patient had no history of cardiac symptoms and had a good exercise tolerance. Patient’s past medical history was significant for alkali (NaOH) ingestion during 1980 for which esophageal resection and a colonic pull-through was performed. Notable aspects of the patient’s history included a father with a brain tumor, 20 pack year history of smoking and a regular consumption of cocaine for chest pain. On physical examination, the patient was alert, cooperative and in slight distress. His vitals were normal except for a blood pressure of 147/83. General examination showed a few slightly enlarged cervical lymph nodes bilaterally. Examination of the chest revealed a 4 × 4 cm midline mass which was extremely tender and inspection of abdomen showed an old surgical scar. In the emergency room the patient received aspirin 325 mg, morphine 4 mg intravenously and famotidine 20 mg intravenously. Baseline laboratory tests including complete blood count, metabolic and coagulation profiles were within normal limits. An unremarkable electrocardiogram (EKG) and three sets of negative troponins excluded a cardiac cause for patient’s chest pain. A Chest X Ray (CXR) revealed a widened mediastinum and a CT Chest was ordered which was eventually extended to include the abdomen and pelvis. This showed a large (11.4 × 8.3 × 12.1 cm) vascular mediastinal mass. This mass was in contiguity with the heart, stomach and aorta, exerting mass effect on the aorta and pulmonary vasculature. The CT scan also revealed multiple round enhancing liver lesions raising the suspicion of a metastatic malignancy with the largest lesion in the left lobe measuring 3.9 cm. GI and Surgery were consulted and an endoscopy and EUS were planned. At endoscopy, a large, ulcerated, cratered and friable mass was found at 29 cm extending to 36 cm at which point the lower anastomosis of the colonic pull through was present. Multiple endoscopic biopsies were obtained and sent for pathology. Fine needle aspiration was attempted under EUS guidance to assess the nature of hepatic lesions. Pathology of the esophago-gastroduodenoscopy (EGD) biopsy revealed colonic mucosa with acute and chronic inflammation, granulation tissue and ulcerative debris. The fragments were highly atypical with hyperchromasia and mitotic activity. The FNA from hepatic lesions were also positive for malignant cells. The immunohistochemical analysis of the EGD biopsy showed that the tumor was immunoreactive with CD117, CD34 and DOG1 while markers of carcinoma, melanoma and lymphoma were negative. In light of the pathology report, the immunohistochemistry and the CT scans, the tumor was classified as a stage 4 GIST of colonic interposition. Subsequent to the biopsy based diagnosis, surgical and radiological treatment modalities were ruled out due to the extent and nature of the tumor. The patient was administered imatinib 400 orally daily, adequate pain control medications and a suitable bowel regimen. Patient continues to do well on 3 months follow up. Follow CT scan shows considerable shrinkage in the size of the tumor Figures and.