Adenosquamous carcinoma arising within a long‐standing intrapulmonary bronchogenic cyst in an adult presenting with hyponatraemia.

A 74-year-old woman with a long-standing intrapulmonary bronchogenic cyst (IPBC) was diagnosed with adenosquamous carcinoma after presenting with persistent hyponatremia. This case represents the first reported instance of such a transformation in an IPBC. The patient underwent surgery and received adjuvant chemotherapy and immunotherapy, achieving remission 2.4 years post-treatment. The study highlights the importance of monitoring bronchogenic cysts for potential malignant transformation, even decades after initial diagnosis. [Extracted from the article]