Pulmonary alveolar proteinosis with lung squamous cell carcinoma

Pulmonary alveolar proteinosis (PAP) is a rare disease characterized by accumulation of periodic-acid-Schiff (PAS)-positive material in the alveolar space (1). Although the cause of this disease is unknown, functionally defective alveolar macrophages or defective clearance of intraalveolar surfactant re-uptake by type 2 pneumocytes have been proposed by some investigators (2,3). In this context, PAP has been reported as a complication of certain diseases such as tuberculosis, haematological malignancy, interstitial pneumonitis or AIDS (48). To our knowledge, we report the first case of extensively developed PAP coexisting with lung squamous cell carcinoma.