A case of malignant mesothelioma detected by endobronchial ultrasound-guided transbronchial needle aspiration

Abstract

Background : We report a case of malignant mesothelioma detected by endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA).

Case : A male in his 60s presented to his local doctor with a history of cough, sputum, and dyspnea on exertion. Imaging examination led to the suspicion of pleural mesothelioma and the patient was referred to our hospital. Chest computed tomography revealed diffuse thickening of the left pleura with irregularities, encapsulated pleural effusion, and multiple enlarged lymph nodes. Cytologically, atypical cells were seen in papillary arrangement with a high N/C ratio or in loose sheet-like clusters with a moderate N/C ratio. The nuclei of the atypical cells were centrally located, and the cells were either mono-or binucleated containing thick polygonal cytoplasm, with cell-to-cell apposition and window-like crevices. Small orange G-positive cells were also observed. Histologically, numerous cell clusters in papillary, micropapillary, and sheet-like arrangements, nuclei with mild irregularities and distinct nucleoli, and binuclei were observed. The results of immunohistochemical analysis supported the diagnosis of malignant mesothelioma.

Conclusion : Although the diagnosis of mesothelioma using EBUS-TBNA may differ from the characteristic findings in fluid specimens, the appearance of small orange G-positive cells may be suggestive of mesothelioma.