342. VIDEO-ASSISTED THORACOSCOPIC ENUCLEATION OF BENIGN SCHWANNOMA MISDIAGNOSED AS MALIGNANT LESION ON F-18 FDG PET/CT IN ESOPHAGEAL SUBMUCOSAL TUMOR

Esophageal SMT is a rare disease, and most of them are benign. Esophageal schwannoma accounts for about 2% among esophageal SMT. Recently, F-18 FDG PET/CT has been widely used to confirm malignancy or to identify other metastatic lesions in cancer patients. However, even benign tumors often show an elevated SUV, and in the case of schwannomas, various values of SUV have been reported, which seems to limit differentiation from other malignant peripheral nerve sheath tumors. A 56-year-old female patient was incidentally found with extrinsic compressing mass at 22 cm from the incisor. An endoscopic ultrasonography and chest CT showed a 3.4 cm sized homogenous well-defined mass in upper esophagus, leiomyoma or gastrointestinal stromal tumor was suspected. SUV was elevated on PET-CT was performed to identify malignancy and metastatic lesions. When confirmed as malignant, additional surgery was planned, and enucleation was performed for primary diagnosis and treatment. The esophageal bulging was confirmed. After dividing the esophageal muscle, and underwent enucleation. In immunohistochemical staining, S-100 protein showed positive findings, which could be diagnosed as schwannoma. Due to the characteristics of esophageal SMT, FDG uptake may be observed on PET-CT, but if there is no evidence of metastasis, it is likely to proceed with treatment according to the benign disease. Then, if immunohistochemistry examination is diagnosed as malignancy, it would be desirable to apply additional stage surgery.