Primary Retroperitoneal Mucinous Cystic Neoplasm: Authors' Experience and Review of the Literature.

INTRODUCTION: Primary retroperitoneal mucinous cystic neoplasm (PRMCN) is a rare retroperitoneal tumor with female predilection. It is classified into 3 types: benign mucinous cystadenoma (MCA), borderline mucinous cystadenoma (MCAb), malignant mucinous cystadenocarcinoma (MCAc). This study retrospectively evaluates the prevalence of PRMCN among retroperitoneal neoplasms resected between June 2006 and January 2015 at a referral center. Authors' experience with PRMCN is reviewed, and a new case of PRMCN, incidentally diagnosed during pregnancy is reported. A literature review using PubMed is also presented, discussing several issues concerning clinicopathologic features, treatment options, and long-term outcome of PRMCN. CASE REPORT: A 36-year-old woman was incidentally diagnosed with a 12-cm retroperitoneal cyst discovered by ultrasound at 36 weeks of gestation. Eight months later the patient was referred to the department of surgery, the Tel Aviv Sourasky Medical Center. By that time, the patient has sensed local discomfort. Physical examination revealed a right abdomen mass with mild tenderness. Computed tomographic scan depicted the cyst, located along the right paracolic gutter, displacing the right colon medially. The patient underwent complete laparoscopic resection of a 15-cm cyst, without its disruption. The cyst was drained inside an endobag and retrieved. The patient was discharged home on postoperative day 1. The pathology was MCA. Long-term result was no evidence of disease for 9 months. DISCUSSION: The prevalence of PRMCN among resected retroperitoneal neoplasms was 1.95% (3/154 neoplasms). The treatment of choice is complete tumor resection. Surgical technique should be chosen depending on the surgeon's expertise and tumor factors affecting safe resection. Surgery timing during pregnancy should be dictated by both risk of malignancy and obstetric considerations. As for malignant PRMCN, radical surgery does not seem justified, especially in reproductive females. Adjuvant chemotherapy should probably be reserved for metastatic disease, recurrence, and tumor rupture. Long-term follow-up is lacking, although it is important to better define the prognosis of PRMCN.