[Alveolar adenoma--a rare pulmonary mass: case report and review of the literature].

This report describes the case of a 58-year-old man presenting with haemoptysis. Chest X-ray and CT scans showed a solitary pulmonary mass in the right lower lobe without radiographic signs of malignancy. Definitive histology following thoracoscopic wedge resection showed the distinctive findings of an alveolar adenoma, a very rare benign tumour of the lung of unknown histogenesis. Its existence was first described in 1986 with less than 30 cases published to this day. Alveolar adenoma usually presents as a peripheral solitary lesion in asymptomatic, older patients. Its histological features, the benign proliferation of alveolar epithelium and septal mesenchyme, allow for its distinction from other benign lesions of the lung. Complete excision is considered curative on the basis of current knowledge.