A case of advanced gastrointestinal stromal tumor (GIST)presenting with paraneoplastic syndrome

Abstract

4242 Background: Paraneoplastic syndromes are common manifestations of many malignancies but have not been reported with gastrointestinal stromal tumors (GIST). Methods: This is a case report of a 51 y/o white male with GIST. Results: The patient presented with dull persistent headache and diplopia. Eye examination revealed diffuse bilateral sixth nerve palsy. Routine laboratory tests and a spinal tap analysis were non-revealing. CT and MRI of the brain were normal. MRI of the orbits showed a mild, diffuse inflammation and thinckening of the extraocular muscles. The patient was treated with prednisone and improved. A few weeks later, the patient developed pleuritic pain and CT of the abdomen revealed a large paraduodenal mass and a second mass measuring 5x8 cm in the left lobe of the liver. The patien had complete resection of the paraduodenal mass and a left hepatic lobectomy. Pathology was consistent with GIST and the surgical margins were free of tumor involvement. The patient was followed without treatment with serial CT scans and also had open liver biopsies which were negative at the time of an incidental cholecystectomy. He remained symptom free for 6 years. Headache and diplopia returned and improved with prednisone. Restaging with CT and PET revealed a new mass in the right lobe of the liver. Biopsies revealed a c-kit positive tumor similar in morphology and immunohistochemical staining to the initial GIST. The patient responded to imatinib with resolution of the PET scan findings though CT continued to demonstrate a large mass. The headache and diplopia have not recurred following discontinuation of the prednisone. Conclusions: The temporal links between symptomatology and the original and recurrent tumors support the hypothesis that the headache and diplopia represent a paraneoplastic syndrome previously unreported for patients with GIST. No significant financial relationships to disclose.