Supplementary Material for: Per-oral endoscopic tumor resection for esophageal leiomyoma with accumulation of fluorine-18-fluorodeoxyglucose: A Case Report

Introduction
Esophageal leiomyomas are relatively common benign esophageal submucosal tumors. Generally, benign tumors don’t accumulate fluorine-18-fluorodeoxyglucose (FDG), but it is not rare for FDG to accumulate in uterine, duodenal, or esophageal leiomyomas. In our case, we performed per-oral endoscopic tumor resection (POET) for an esophageal leiomyoma with FDG accumulation.
Case Presentation
A 40-year-old female with a history of surgery for right breast cancer underwent fluorine-18-fluorodeoxyglucose-positron emission tomography (FDG-PET) for surveillance examination. A subepithelial tumor with intense FDG uptake (SUV max, 5.49) was detected in the middle thoracic esophagus. The lesion appeared as a low-absorption area on contrast-enhanced CT and was confirmed to have an equivalent signal level as muscle tissue on MRI T2WI. Endoscopic examination revealed submucosal tumor 25 cm from the incisors. Endoscopic ultrasonography (EUS) revealed a 20 mm low-luminance mass, mainly located in the second and third layers. The histopathology diagnosis by EUS-fine-needle aspiration was leiomyoma. We decided to treat it with per-oral endoscopic tumor resection (POET) because malignancy could not be ruled out. The tumor was excised en bloc using POET without severe complications. The tumor diameter was 19×15 mm and disordered spindle cells were observed. Desmin and αSMA were positive and S100 protein was negative om immunohistochemical study. Therefore, the pathological diagnosis was a leiomyoma.
Conclusion
In the present case, glucose transporter 1 expression was negative; however, we examined why the leiomyoma accumulated FDG. We suggest that awareness of leiomyoma with the accumulation of FDG is exist in clinical practice.