A large cystic mass was found in the subdiaphragmatic region of a 46-year-o
ld woman who had complained of continuous pain in the left flank,The cyst w
as located in the retroperitoneum just below the diaphragm and was adhered
to the diaphragmatic skeletal muscle and abdominal aorta, but was separate
from the spleen, pancreas, left adrenal gland and left kidney. The surgical
ly resected cyst measured 8 x 8 x 7 cm and was filled with protein-rich flu
id, which contained amylase and embryonal proteins such as carcinoembryonic
antigen, CA125 and CA19-9. Histologically, the cyst wall was composed of a
fibrovascular connective tissue containing thin smooth muscle layers and m
ucus-secreting glands and was lined by a ciliated pseudostratified or tall
columnar epithelium without dysplastic changes. Thus, a diagnosis of bronch
ogenic cyst, which is usually discovered in the posterior part of the media
stinum, was made. A rare case of bronchogenic cyst and a literature review
is presented.