A Case of Mediastinal Granular Cell Tumor Diagnosed via Endobronchial Ultrasound-guided Transbronchial Mediastinal Tumor Biopsy

In this report, we present a case of granular cell tumor (GCT) of the mediastinum diagnosed using endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) biopsy. A 60-year-old woman was referred for the evaluation of a superior mediastinal mass (30 × 40 mm) at the level of the aortic arch with abnormal uptake on 18F-fluorodeoxyglucose positron emission tomography-computed tomography. Upper gastrointestinal endoscopy revealed no tumor; however, stricture was found in the upper esophagus, 20 cm from the incisors. Although a transnasal endoscope (GIF-XP290N; outer diameter at the distal end 5.4 mm, Olympus Medical System, Tokyo, Japan) could be advanced beyond the stricture, endoscopic ultrasound-guided fine-needle aspiration could not be conducted because the scope (FUJINON EG530UT2; outer diameter at the distal end 13.9 mm, Fujifilm Co., Tokyo, Japan) could not be advanced beyond the stricture. Thus, the mediastinal mass was biopsied under EBUS-TBNA, and nests of cells with granular eosinophilic cytoplasm were found, in which pathologically and immunohistochemically, GCT was suggested. The case points out that EBUS-TBNA can be useful for GCT diagnosis in the mediastinum, which is challenging to diagnose via gastroscopy.