A case of solitary squamous cell papilloma in a bulla of the peripheral lung

Abstract

A 79-year-old man with a medical history of bladder and prostate cancer was referred to our respiratory department because of an enlarged pedunculated nodule in a bulla of the right lung, S9 peripheral, detected on chest computed tomography (CT). Bronchoscopy did not yield a definitive diagnosis of the nodule. A metastatic lung tumor or primary lung cancer was suspected because the nodule showed a high uptake of ¹⁸F-fluorodeoxy glucose on positron emission tomography. Therefore, we performed right lung S8-9 segmentectomy by video-assisted thoracic surgery. The pathological diagnosis was solitary squamous cell papilloma, which showed papillary growth with fibrovascular interstitial and stratified squamous epithelia with mild atypia. Part of the bronchus could be observed on the surface of the bulla. We considered that the bulla had been formed by air trapping due to endobronchiolar obstruction caused by the papilloma. Typical CT findings are rarely reported. Squamous cell papilloma should be included in the differential diagnosis of a solitary pulmonary nodule in a bulla.