A teen girl who was very thin had an ultrasound that showed what looked like an adrenal tumor, but during laparoscopic surgery doctors discovered a 6‑8 cm cyst behind the kidney. The cyst turned out to be a rare retroperitoneal bronchogenic cyst, a type of birth‑defect cyst normally found in the chest, not the abdomen. Microscopic analysis showed it was lined with ciliated airway‑type cells and mucus glands, with no cartilage or gut lining.

The retroperitoneal bronchogenic cyst is an extremely rare anomaly. During the examination of an 18-year-old female patient due to her extreme thinness, the abdominal ultrasound and later the CT indicated as an accidental finding--a left side adrenal/suprarenal adenoma, which turned out to be hormonally inactive. But while we were doing a laparoscopic surgical intervention we found a 6-8-cm cyst in the retroperitoneum, between the greater curvature and the spleen. It contained light grey, mucinous liquid. The left suprarenal gland had normal size and appearance. During the microscopic examination the removed terime showed cystic structures, which were covered inside with multilayer ciliated columnar epithelium, mucous excretory glands, a whole layer of connective/interstitial and smooth muscle tissue. Neither cartilage, nor gastrointestinal epithelium was found. Only a few publications have reported about retroperitoneal bronchogenic cyst so far. These lesions occur very rarely at the greater curvature. Although this alteration is really unusual, bronchogenic cysts have to be expected in the differential diagnostics of the retroperitoneal tumors.