Jie Luo, Ruixiang Qin
BACKGROUND Bronchogenic cysts (BCs) are rare congenital anomalies that are extremely uncommon in the retroperitoneum; in this uncommon anatomical location, they are frequently misdiagnosed radiologically as solid adrenal or pancreatic tumors. This report aims to enhance clinical awareness and diagnostic vigilance regarding ectopic retroperitoneal bronchogenic cysts (ERBCs) that closely mimic other common endocrine or urological entities. CASE REPORT We report a case of a middle-aged man presenting with recurrent right flank pain. Abdominal computed tomography (CT) demonstrated multiple right renal calculi with mild hydronephrosis and a well-defined, homogeneous nodular lesion in the right adrenal region. Notably, the lesion exhibited a high unenhanced density (mean 48.79 HU), mimicking a solid adrenal neoplasm. Following comprehensive hormonal and biochemical evaluations, a multidisciplinary team determined that a retroperitoneal tumor could not be ruled out. The patient subsequently underwent laparoscopic resection of the retroperitoneal mass combined with right ureteral stent placement. Intraoperative exploration revealed a morphologically regular adrenal gland and a separate 4×2.5×1.5 cm oval mass located on the psoas major muscle. Histopathological examination confirmed the diagnosis of a benign bronchogenic cyst, characterized by a cyst wall containing prominent cartilaginous components, smooth muscle, and a lining of pseudostratified ciliated columnar epithelium. The patient recovered uneventfully, with complete symptom resolution. CONCLUSIONS ERBCs should be included in the differential diagnosis of non-functional lesions in the periadrenal region, especially when atypical high CT attenuation creates diagnostic ambiguity. Minimally invasive laparoscopic excision remains the gold standard for management.