Search

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., Competing Interests: Conflicts of Interest and Source of Funding: Supported by the Society for Pediatric Pathology Young Investigator Grant (J.P.). The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Objective: Rare disease Background: Isolated systemic arterial supply to normal (unsequestered) lung (ISSNL) without associated pulmonary malformation is rare, and lies towards the milder end of the spectrum of congenital lung abnormalities. Aneurysmal dilatation of the anomalous artery is an infrequent complication, with only 5 published cases thus far. Case Report: We present the case of a 61-year-old man whose screening chest radiograph showed a retrocardiac mass. Further evaluation with axial imaging demonstrated an ISSNL, complicated by aneurysmal dilatation. The genesis of this condition has been postulated to be due to persistence of primitive aortic branches to the developing lung bud. Initially reported in 1777, this entity is now more accurately classified within the spectrum of pulmonary and bronchovascular abnormalities, with refinement of the latter. The origin of an aberrant artery from the aorta implies that a higher-pressure systemic circulation is being shunted into a lower-pressure pulmonary circulation. While these supplying arteries are known to be large, aneurysmal dilation is exceptionally rare. Here, we review the cases published in the literature and present a case of our own. We aim to describe its pathogenesis, and touch on the classification systems and management. Conclusions: ISSNL is usually first suspected on a screening chest radiograph, as many patients are asymptomatic. Based on contrast-enhanced axial imaging, the diagnosis can be established non-invasively. Definitive management includes surgical and endovascular techniques. [ABSTRACT FROM AUTHOR]