Rhabdomyomatous Dysplasia of the Lung

Abstract

This article deals with the presence of nontumoral striated muscle fibers in the lungs of 3 neonates. These cells were diffusely distributed in one lung (case 1) or in both (case 2), or focally localized to the lung parenchyma adjacent to the liver in a case with a large right diaphragmatic hernia (case 3). The striated muscle fibers were located in the walls of small bronchi and bronchioli or in the alveolar interstitium. Other major lung malformations found simultaneously were absence of lobation, hypoplastic lungs, and hypoplastic pulmonary vessels. The origin of striated muscle fibers in the neonatal lung has been attributed to anomalous differentiation of mesoblastic cells (as in cases 1 and 2). The presence of striated muscle cells in the lower margin of a hypoplastic lung associated with a right diaphragmatic hernia (case 3) suggests that intrapulmonary inclusion of diaphragmatic muscle fibers might be a source as well. Striated muscle fibers in the lung are commonly associated with major malformations involving heart and lungs, suggesting a much wider morphogenetic error.

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

“…The first child 2 died at age 4 months; the other 3 died prenatally. Similar cases were described by Drut et al, 4 Vilanova et al, 5 and Chen et al 6 As was the case with our patient, the infants were female. Only two cases have been described in male patients.…”

Two sisters with cardiac‐urogenital syndrome secondary to pathogenic splicing variant in the MYRF gene with unaffected parents: A case of gonadal mosaicism?

“…In our first patient, among others, a very rare rhabdomyomatous dysplasia of the lung (presence of striated muscle in the lung parenchyma) was described, which is associated with significant malformations involving the heart and lungs. Drut et al (1988) described the autopsy findings of three neonates with rhabdomyomatous pulmonary dysplasia in great detail (Drut et al, 1988). Other findings described in two of these three patients were phenotypically very similar to the cardiac‐urogenital syndrome.…”

Rhabdomyomatosis of the newborn lung unassociated with other malformations

“…The finding of striated muscle fibres in the lung is a rare occurrence, mainly seen in benign or malignant tumours of the lung 9 . Only a few reports of nontumoral rhabdomyomatosis of the lung have been described [1][2][3][4][5][6]8,[10][11][12][13][14][15] . Clinical and pathological data of patients with rhabdomyomatosis of the lung are summarized in Table 1.…”

“…Thus, if a displacement from the pulmonary bud occurs in earlier stages of development, before the separation of the bud from the oesophagus is completed, fragments of the oesophagic striated muscle cells could be incorporated into the lung parenchyma. This theory would be supported by the occasional association of congenital diaphragmatic hernia with the presence of skeletal muscle fibres in the lung parenchyma [2][3][4][5] . The possibility that the striated muscle cells in the lung could be of cardiac origin has been also postulated.…”

“…The presence of non-neoplastic striated muscle fibres in the lung is an exceedingly rare congenital malformation with few cases reported in the literature. Most cases have been associated with underlying developmental anomalies, including extralobar and intralobar pulmonary sequestration [1][2][3][4] , congenital diaphragmatic hernia [2][3][4][5] , and cystic adenomatoid malformation of the lung [6][7][8] .…”