Transurethral Resection of a Bladder Tumor in Pregnancy: Decidual Reaction Bladder Endometriosis

Background: Decidual reaction bladder endometriosis (DRBE) is exceedingly rare with few reported cases in the literature. It presents as a bladder mass during pregnancy, and may be accompanied by lower urinary tract symptoms. Histologic diagnosis is necessary to rule out primary bladder malignancy. We present a case of a bladder tumor identified during pregnancy. The mass was managed endoscopically and found to be DRBE, a rare benign entity. Case Presentation: We present a 31 year old 15 weeks pregnant nonsmoker woman with a rapidly enlarging bladder mass concerning for primary bladder malignancy. Mass confirmed on formal renal/bladder ultrasound and in-office cystoscopy. After informed consent was obtained, the patient was taken to the operating room. A 5.5 cm bladder mass, with an atypical nodular appearance and minor calcifications, was identified. Transurethral resection of the mass was performed. Final pathology report showed florid endometriosis with stromal decidualization. Final diagnosis: pregnancy induced vesical decidualized endometriosis simulating a bladder tumor. Patient continued routine obstetrics follow-up, and has experienced no pregnancy-related complications. Three months after delivery the patient will follow up with outside urology provider for cystoscopy, and subsequent surgical management should it be necessary. Conclusion: DRBE is a rare benign bladder mass that presents in pregnancy. It can grow rapidly raising concern for an aggressive primary bladder malignancy. Any bladder mass identified in pregnancy should undergo early, appropriate work-up given the potential risk for bladder cancer. After diagnosis, DRBE is most often managed conservatively. After delivery, should the patient experience ongoing urinary symptoms, medical and surgical treatment options are available. Overall, DRBE is considered rare, but should be considered in the differential diagnosis for any bladder mass presenting during pregnancy.