A tumorous type of pulmonary rhabdomyomatous dysplasia

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.

Rhabdomyomatous dysplasia of the newborn lung associated with multiple congenital malformations of the heart and great vessels

Interstitial proliferation of striated muscle in the lung is extremely rare. Most cases are associated with other congenital malformations, such as lung sequestration, diaphragmatic hernia, or cardiac malformations. We describe a newborn with rhabdomyomatous dysplasia of the lung associated with multiple congenital malformations of the heart and great vessels. The female neonate was born at 37 weeks of gestation as the second child to a 31-year-old woman without relevant previous medical or family history. In week 26 of gestation, a complex heart malformation and polyhydramnion were diagnosed by ultrasound. Postnatally, right lung hypoplasia, a bilobar right and left lung, anomalous drainage of the pulmonary veins, atrial and ventricular septal defects, and double-outlet right-ventricle and multiple aortopulmonary collaterals were described. Histological examination of a biopsy of the right lung demonstrated the presence of numerous bundles of striated muscle fibers arranged randomly in the pulmonary interstitium. Unilateral resection of the right lung was not a therapeutic option, because the left lung had developed bronchopulmonary dysplasia with severe reduction in gas exchange as a consequence of long-term mechanical ventilation. Symptomatic relief and palliative cardiac surgery were offered. At age 5 months, the infant died of a pulmonary hemorrhage following cardiac surgery.