Pulmonary rhabdomyomatous dysplasia of the newborn in neurofibromatosis type 1.

Proliferation of non-neoplastic striated muscle cells in the lung is rare and has been frequently observed in cases of cardiovascular and pulmonary congenital malformations. We present an extremely rare case of pulmonary rhabdomyomatous dysplasia (RD) in neurofibromatosis type 1 (NF-1). A male neonate was born at 35 weeks' gestation after normal pregnancy. Postnatally, besides patent ductus arteriosus and posterior mediastinal mass, abnormal cystic lesions in the left upper and lower lung were detected. No bronchial atresia and stenosis were identified. Partial lobectomy specimens showed hypoplastic lung parenchyma with cystic lesions resembling terminal bronchioles and distinctive proliferation of non-neoplastic striated muscle fibers in the interstitium. The posterior mediastinal mass consisted of neurofibroma. Considering that café au lait spots and freckling occurred at 2 months of age, a diagnosis of NF-1 was made. The patient died of aspiration pneumonia at the age of 30 months. To the best of our knowledge, this is the first case of pulmonary RD in NF-1.