Nodules, masses, and pseudomasses in the pediatric lung.

The vast majority of pulmonary masses in children are nonmalignant. Most pediatric nodular disease is granulomatous in origin. Infections and congenital lesions outnumber neoplastic lesions. Pulmonary metastatic disease most often results from Wilms' tumor and is followed in frequency by the sarcomas. Primary pulmonary malignancy is rare in the child.