Retroperitoneal bronchogenic cyst mimicking pancreatic cystic lesion.

Retroperitoneal bronchogenic cyst is detected extremely rarely and often masquerades as other diseases. Here, we report 2 cases of retroperitoneal bronchogenic cyst mimicking pancreatic mucinous tumor. Histologically, both cysts were composed of ciliated respiratory-like epithelium with abundant mucin content, smooth muscle bundles and mature cartilage, compatible with the diagnosis of retroperitoneal bronchogenic cyst. In addition to these 2 cases, another 42 retroperitoneal bronchogenic cysts reported in the English literature were collected for review and analysis. Twelve (28%) were located over the peripancreatic area. Just over half (51%) of them were asymptomatic. No accurate preoperative diagnosis could be made for any of the lesions. About a third (33.3%) of the peripancreatic retroperitoneal bronchogenic cysts masqueraded as pancreatic cystic lesions.