Immunohistochemical phenotype of the urinary bladder endocervicosis: Comparison with normal endocervix and well‐differentiated mucinous adenocarcinoma of uterine cervix

Endocervicosis of the urinary bladder is a very rare tumor‐like benign lesion. In the present report, a case in a 34‐year‐old woman, who has a prior Caesarean section at the age of 30 and 2‐years history of dysuria, is described. Transvaginal ultrasound, cystoscopy and magnetic resonance imaging demonstrated a solid mass in the posterior wall of the bladder. The mass was removed and histology revealed a haphazard proliferation of endocervical‐type mucinous glands scattered through the muscularis propria of bladder wall. Immunohistochemical phenotype of these glands was compared with three normal uterine endocervices and two cases of well‐differentiated mucinous adenocarcinoma of the uterine cervix. Endocervicosis glands displayed positive reaction for antibodies against estrogen receptor, progesterone receptor, CAM 5.2, cytokeratin 7, CA125, HBME‐1 and carcinoembryonic antigen, which showed positivity in normal endocervices. On the other hand, only glands of well‐differentiated mucinous adenocarcinoma expressed human gastric mucin and showed high proliferative index of Ki‐67. These results supported the hypothesis of its Müllerian origin. Furthermore, diffuse distribution of estrogen and progesterone receptors, lack of human gastric mucin and low proliferative activity were distinct features for endocervicosis compared to well‐differentiated mucinous adenocarcinoma.