Abstract
Introduction Rhabdomyomatous dysplasia (RD) is a pathologic finding in CPAMs that was incorrectly
attributed to their malignant potential. The increasing recognition of extrathoracic
(intradiaphragmatic and intraabdominal) congenital pulmonary airway malformations
(CPAMs) offers a clue to the origin of RD. We hypothesize that the presence of RD
is related to the CPAM's anatomic location.
Materials and Methods Retrospective review was performed of all children who underwent resection of a CPAM
during a 10-year period. The age at the time of operation, location of the CPAM, and
pathologic findings were collected. Peridiaphragmatic location was defined as within
the inferior pulmonary ligament, deep to the diaphragmatic portion of the parietal
pleura (“intradiaphragmatic”) or adjacent to the abdominal side of the diaphragm.
Statistical analysis was performed using Fisher's exact test for 2 × 2 tables.
Results Twenty-six patients with CPAM were identified. Preoperative imaging was performed
by computed tomography (CT) scan (16/26), ultrasound (5/26), magnetic resonance imaging
(MRI) (1/26), and chest radiograph (4/26). The median age at resection was 15 months.
Of these, 16 were pure cystic adenomatoid malformations, 4 were extralobar sequestrations,
4 were intralobar sequestrations, and 2 were bronchogenic cysts. Nine lesions were
peridiaphragmatic with four being intradiaphragmatic (44%). Eight of the nine resected
peridiaphragmatic lesions contained histologic evidence of rhabdomyomatous changes
(89%, confidence interval [CI] 52–99%). None of the other lesions contained RD (CI
0–19%, p < 0.001).
Conclusion RD was seen exclusively, and in virtually all peridiaphragmatic CPAMs. While the
exact significance of RD remains unclear, it may represent incorporation of striated
muscle tissue associated with the developing diaphragm.
Keywords
congenital pulmonary airway malformation - rhabdomyomatous dysplasia - diaphragm
