Polypoid Endometriosis, a Benign Tumor with Perplexing Radiologic Features: A Case Report

Polypoid endometriosis is a rare form of endometriosis. It is a benign variant but its radiologic findings trick clinicians into concern about the tumor being malignant. A 42-year-old patient with a history of dysmenorrhea and adenomyosis presented a 60 mm-sized mass in the Douglas pouch with irregular echogenicity. The patient went under the first surgery for tumor removal, and its histopathologic diagnosis was endometriosis. We started daily dienogest medication to suppress tumor recurrence, but after 10 months we decided to stop the medication due to the side effects. Four months after the cessation, a new tumor recurred and after few months of observation, we performed the second surgery of tumor removal and total hysterectomy because of adenomyosis. The tumor was located in the retroperitoneal space in the Douglas pouch with severe adhesions. After the second surgery, the tumor marker Cancer antigen-125 level was normalized and the histopathologic result was endometriosis, which we concluded as polypoid endometriosis.