Müllerian cyst of the uterus treated with laparoscopy and diagnosed using immunohistology

Among uterine cystic tumors, uterine cyst arising from secondary Müllerian epithelium is exceedingly rare. A 45‐year‐old woman presented with pelvic cystic mass, which was initially diagnosed as a paraovarian cyst by ultrasound and magnetic resonance imaging. At laparoscopy, the cyst proved to be a pedunculated uterine cyst, which was easily resected. Histologically, the cyst wall was lined by fallopian epithelium and positively stained for WT‐1, estrogen receptor, and progesterone receptor. The final diagnosis was Müllerian cyst of the uterus. Preoperative diagnosis of uterine Müllerian cyst is usually impossible. Laparoscopy is useful as a minimally invasive treatment to diagnose and resect the cyst at the same time. Specific immunostaining is useful to make a definite diagnosis of Müllerian cyst of the uterus.