Miillerian duct cysts are remnants of the embryologic paramesonephric ducts. When remnants persist in the vagina, the patient may present with a cyst, which is usually asymptomatic and < 2.0 cm in diameter.
A 33-year-old woman with a 4-year history of a cystic vaginal mass presented after the cyst rapidly enlarged and protruded. She reported discomfort with walking and increased vaginal pressure. The pedunculated, 8-cm cyst was surgically removed. Pathology revealed miillerian duct origin.
Although millerian duct cysts are commonly described as small and located in the anterolateral vaginal wall, they should be included in the differential diagnosis of any large, protruding vaginal mass.