Congenital pulmonary airway malformation mimicking lung cancer in adults: a pitfall in oncologic diagnosis.

Congenital pulmonary airway malformation (CPAM) presenting as a solid or solid‑cystic mass on computed tomography (CT) is rare in adults. Its imaging features can closely resemble those of primary lung cancer, often leading to misdiagnosis and adversely influencing clinical decision-making. This dual‑center retrospective case series included adult patients who were radiologically diagnosed with lung cancer but then surgically confirmed to have CPAM between January 2010 and December 2025. Two senior cardiothoracic radiologists jointly reviewed the CT images to evaluate basic lesion characteristics (size, location, and morphology), malignancy‑mimicking signs that prompted the misdiagnosis (e.g., lobulation, spiculation, and pleural retraction), and benign indicators that had been overlooked (e.g., internal microcysts, bronchial communication, and long‑term stability). Descriptive statistics were applied. Ultimately, six patients (two males and four females) with a median age of 59.5 years (range, 36-62 years) were included. The mean lesion diameter was 22.3±8.5 mm. Among the lesions, three were solid‑cystic (all communicating with bronchi), and three were solid (one showing marginal calcification). The misdiagnosis‑related "malignant" features included lobulation (n=3), spiculation (n=3), and pleural retraction (n=3). All three contrast‑enhanced lesions demonstrated mild homogeneous enhancement, with a mean venous‑phase enhancement value of 18.7±3.2 HU. Postoperative pathology confirmed CPAM with no evidence of malignancy. In conclusion, adult CPAM appearing as a solid or solid‑cystic mass on CT poses a considerable diagnostic challenge due to its striking resemblance to lung cancer.