Solitary bronchioloalveolar adenoma of the lung

A case of an unusual pulmonary neoplasia, called bronchioloalveolar adenoma of the lung, is reported. The neoplasm presented as a solitary peripheral lesion of the left lung on computed tomography. Examination of the tumor revealed a focal proliferating lesion consisting of cuboidal or peg-shaped epithelial cells with slight nuclear atypia. Immunohistochemical study with anti-carcinoembryonic antigen antibody, anti-surfactant apoprotein antibody, and anti-Clara cell antibody suggested that this neoplasia has the characteristics of a type II pneumocyte. It is likely that more of these small peripheral lesions, which have potential for evolution to carcinoma, will now be encountered due to the introduction of helical CT of the chest.