Lung squamous cell carcinoma in pulmonary alveolar proteinosis.

Pulmonary alveolar proteinosis (PAP) is a rare pulmonary disease characterized by alveolar accumulation of surfactant. There are only four sporadic PAP case reports associated with lung cancers. These case reports describe only that lung cancer might develop subsequently or coincidently with PAP. Here, we report a case of PAP associated with lung squamous cell carcinoma. This patient with PAP was a 57-year-old man, who had smoked one and a half pack of cigarettes per day for 30 years. In this case, PAP increased with lung cancer developing and disappeared after lung cancer resection. PAP may be the result of the lung squamous cell carcinoma developing in this case.