Nya D. Nelson, Feng Xu, William H. Peranteau, Marilyn Li, Jennifer Pogoriler
Hospital of the University of Pennsylvania. The Children’s Hospital of Philadelphia and Perelman School of Medicine at the University of Pennsylvania.
United States
American Journal of Surgical Pathology
Am J Surg Pathol 2023; 47: 568-579
DOI: 10.1097/PAS.0000000000002025
Abstract
Congenital pulmonary airway malformations (CPAMs) have a range of morphologies with varying cyst sizes and histologic features (types 1 to 3). Evidence suggested they arise secondary to bronchial atresia, however, we recently showed that cases with type 1 and 3 morphology are driven by mosaic KRAS mutations. We hypothesized that 2 distinct mechanisms account for most CPAMs: one subset is secondary to KRAS mosaicism and another is due to bronchial atresia. Cases with type 2 histology, similar to sequestrations, would be related to obstruction and therefore negative for KRAS mutations regardless of cyst size. We sequenced KRAS exon 2 in type 2 CPAMs, cystic intralobar and extralobar sequestrations, and intrapulmonary bronchogenic cysts. All were negative. Most sequestrations had a large airway in the subpleural parenchyma adjacent to the systemic vessel, anatomically confirming bronchial obstruction. We compared morphology to type 1 and 3 CPAMs. On average, type 1 CPAMs had significantly larger cysts, but there remained substantial size overlap between KRAS mutant and wild-type lesions. Features of mucostasis were frequent in sequestrations and type 2 CPAMs, while their cysts were generally simple and round with flat epithelium. Features of cyst architectural and epithelial complexity were more common in type 1 and 3 CPAMs, which rarely showed mucostasis. Similarity in histologic features among cases that are negative for KRAS mutation support the hypothesis that, like sequestrations, the malformation of type 2 CPAMs is related to obstruction during development. A mechanistic approach to classification may improve existing subjective morphologic methods.
Category
Class III. Pulmonary Hypertension Associated with Lung Hypoplasia
Abnormal Systemic to Pulmonary Arterial Collaterals or Connections
Genetic Factors Associated with Pulmonary Vascular Disease
Age Focus: Pediatric Pulmonary Vascular Disease
Fresh or Filed Publication: Filed (PHiled). Greater than 1-2 years since publication
Article Access
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