Proximity to the Diaphragm Predicts the Presence of Rhabdomyomatous Dysplasia in Congenital Pulmonary Airway Malformations
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In brief
In brief
Study of 26 pediatric CPAM cases reveals rhabdomyomatous dysplasia occurs almost exclusively in lesions located near the diaphragm (89% of peridiaphragmatic vs 0% of other locations). Findings suggest RD may result from incorporation of diaphragmatic muscle during development rather than indicating malignant potential.
Written by the GCMD Library team from the article.
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.