Alveolar adenoma of the lung: a clinicopathological description of a case of this very unusual tumour.

Alveolar adenomas are extremely rare, and are probably benign lung tumours of unknown histogenesis. This report describes a case of alveolar adenoma in a 43 year old white man, who presented with pleuritic chest pain. A chest x ray and computerised tomography scan demonstrated a solitary left lower lobe lung nodule. Although a positron emission tomography scan seemed to document the benign nature of the lesion, a thoracoscopic wedge resection was performed to alleviate the symptoms and verify the diagnosis. Histologically, the lesion was well demarcated, dominated by large and small cysts with no normal lung parenchyma. The interstitial cellular component consisted of both epithelioid and vaguely spindle shaped cells. The cystic cell linings were mostly indistinct, although areas of cuboidal epithelial cells were seen. Multiple histochemical and immunohistochemical tests were performed. There were no histological signs of malignancy and the patient is doing well one and a half years postoperatively.