Pulmonary alveolar proteinosis. A report of two cases with diagnostic features in bronchoalveolar lavage specimens

Pulmonary alveolar proteinosis (PAP) is a rare condition that has been associated with myriad diseases and disorders. Alveolar spaces are progressively filled with a phospholipoproteinaceous material, presumably related to a derangement of surfactant production and/or catabolism. The cytologic features of PAP in bronchoalveolar lavage (BAL) sediments are unique, and recognition of these characteristics can help guide clinical intervention.

A 47-year-old male with a history of progressive dyspnea and recent pneumonia presented with a five-lobe alveolar infiltrate and subsequently underwent bronchoscopic examination. A 31-year-old female with chronic myelogenous leukemia in blast transformation developed unresponsive pulmonary infiltrates necessitating bronchoscopy with lavage. Both BAL lavage fluid sediments contained a homogeneous, basophilic, granular material typical of PAP. The material was composed of extracellular, multilamellated bodies when viewed by electron microscopy. Both patients required repeated therapeutic whole lung lavage, and one died of the disease eight months after the diagnosis.

Clinical presentation, grossly milky BAL fluid and fluid sediment with light microscopic findings of basophilic, periodic acid-Schiff-positive, granular debris with cholesterol crystals and a few alveolar macrophages suggest this process. The light microscopic findings can be confirmed by ultramicroscopic demonstration of extracellular multilamellated bodies. BAL with appropriate examination of the effluent sediment facilitates the diagnosis of PAP.