Pulmonary alveolar proteinosis in infants.

We investigated the histological and molecular characteristics of pulmonary alveolar proteinosis (PAP) in two siblings (a brother and sister) who did not exhibit respiratory distress at birth but who each developed symptoms during infancy. Histological analysis of lung specimens showed positive staining for surfactant proteins in both patients. The polymerase chain reaction revealed expression of messenger RNA for surfactant protein B (SP-B) in the lung specimens. No defect in SP-B which is characteristic of the congenital form of PAP was observed. The concentration of surfactant protein A (SP-A) in bronchial alveolar lavage (BAL) fluid was elevated in patient 1 suggesting the BAL concentration of SP-A may be a clue to the diagnosis of this form of PAP.

Conclusions: The accumulation of surfactant protein A in two siblings with an infantile form of pulmonary alveolar proteinosis could be a clue to the diagnosis.