A 71-year-old man was worked up for squamous cell carcinoma of the esophagus (T4N1Mx). In the course of the workup, a 4cm mass posterior to the stomach was discovered. CT guided biopsy of the retrogastric mass showed a gastrointestinal stromal tumor with rare mitotic figures. His esophageal carcinoma was successfully treated with chemoradiation, and at one year post treatment, there was no clinical evidence of disease. EGD with biopsy, and PET scan were both normal. Repeat CT scan (shown above) showed no change in size of the GIST over the course of the year. The patient, who was asymptomatic, was given the choice of observation or resection of the GIST. The surgical recommendation was for resection because of the potential for malignant change within the GIST, and the resistance to chemotherapy of such lesions, and the patient agreed.