Cytopathology of pulmonary alveolar proteinosis complicating lung transplantation.

Pulmonary alveolar proteinosis is a disorder of unknown origin that occurs rarely after lung transplantation. We identified a patient with pulmonary alveolar proteinosis 66 days after undergoing single lung transplantation for idiopathic pulmonary fibrosis. We based the diagnosis on the presence of amorphous clumps or globules of acellular and finely granular material in bronchoalveolar lavage fluid (BALF). This material persisted for an 18.5-month period and was present in 9 of 14 lavage specimens. However, despite its presence in the native lung at autopsy, the material was seen in only 1 of 14 transbronchial lung biopsy specimens. Although uncommon, pulmonary alveolar proteinosis can be diagnosed readily in BALF by its distinctive cytopathologic features and should be considered in the differential diagnosis of pulmonary disease in lung transplant recipients.