Pulmonary alveolar proteinosis in children.

Three cases of childhood pulmonary alveolar proteinosis (PAP) are presented with emphasis on the radiographic findings on plain chest films and computed tomography. Three different radiographic patterns may be seen on chest radiography: (1) reticulonodular, (2) small acinar nodular mimicking miliary disease, and (3) coalescense of various-sized acinar nodules leading to focal consolidation. Absence of cardiomegaly, pleural effusions, or adenopathy are important differential points. Chest computed tomography (CT) shows scattered linear densities and areas of focal coalescence corresponding to filled alveoli, most prominently at the lung bases. Radiographic improvement after lavage is due to decrease in the amount of periodic acid-Schiff (PAS)-positive material within the alveoli. Progressive enlargement of acini during childhood may account for the variable pattern seen in PAP in children and contrasts to the more confluent pattern found in the adult. CT is of limited value in diagnosis or management of PAP. Although detailed examination of sputum and bronchopulmonary washings may yield diagnosis, open lung biopsy is required for confirmation.