Retroperitoneal bronchogenic cyst masquerading as an adrenal incidentaloma.

Summary: Bronchogenic cysts, developmental malformations of the primitive foregut, extremely rarely occur in the retroperitoneum. Here, we present a retroperitoneal bronchogenic cyst presenting as an adrenal incidentaloma and masquerading clinically as a phaeochromocytoma. Learning points: Retroperitoneal bronchogenic cysts are exceptionally rare, particularly presenting as adrenal incidentalomas (AI), and can mimic other conditions such as non-functioning phaeochromocytomas. This case emphasises the need to consider rare conditions such as retroperitoneal bronchogenic cysts in the differential diagnosis of AI, especially when imaging findings are unusual despite normal hormonal studies. Atypical adrenal masses still warrant surgical evaluation and histopathological analysis to confirm the diagnosis and exclude rare entities. The occurrence of retroperitoneal bronchogenic cysts highlights the importance of understanding embryogenesis, particularly the migration pathways and foregut development. Histopathological examination remains crucial for diagnosing bronchogenic cysts, as they demonstrate the characteristic ciliated columnar epithelium with subepithelial smooth muscle, seromucinous glands, and cartilage.