Mixed squamous cell and glandular papilloma of the lung―A case report and literature review in Japan

INTRODUCTION: Mixed squamous cell and glandular papilloma (MSGP) of the lung is rare neoplasm, only 19 cases previously reported in Japan. MSGP is one of three separate categories of solitary endobronchial papillomas, which account for less than 0.5 % of all lung tumors. MSGP is rarest of the three. We present a rare case of MSGP and review the literature in Japan. PRESENTATION OF CASE: A 49-year-old man presented with a nodulous shadow in the right lower lung field identified on a chest X-ray performed for back pain. Computed tomography demonstrated a well-circumscribed, 9-mm mass in the S8 segment of the right lower lung lobe. Positron emission tomography showed accumulation of 18F-fluorodeoxyglucose in the tumor with a standardized uptake value of 2.29. Following thoracoscopic partial resection, adenocarcinoma was diagnosed by frozen section, and radical segmentectomy of S8 was performed. The final diagnosis was mixed squamous cell and glandular papilloma. The patient had an uncomplicated postoperative course and remains asymptomatic 3 years after the procedure. DISCUSSION: The etiology and pathological characteristics of MSGP remain unclear. There has been no report of recurrence in MSGP cases treated with complete resection; thus, limited resection that preserves pulmonary function is desirable. Further data including new cases are required. CONCLUSION: We present a rare case of mixed squamous cell and glandular papilloma (MSGP) of the lung and review the literature in Japan. Limited resection that preserves pulmonary function, while ensuring complete resection, is desirable. Further investigations with new cases are required.