Primary pulmonary rhabdomyosarcoma of the lung in children. Report of two cases presenting with spontaneous pneumothorax.

This report describes two cases of pulmonary rhabdomyosarcoma occurring in children, ages 21 and 30 months at diagnosis. Both patients presented with spontaneous pneumothorax and had cystic changes in the affected lung by chest x-ray. Ultrastructural and immunohistochemical studies supported the myogenic phenotype of these neoplasms. The authors were unable to confirm that either of these tumors had unequivocally originated in a congenital cyst although previous authors have reported this association. An apparent morphologic spectrum of embryonic appearing neoplasms including pulmonary blastoma and a malignant mesenchymoma have been observed in the lungs of children.