Abstract
Objective: To collaborate with the number of published cases, given the scarcity in the world literature and rarity of the disease studied, contributing to the propaedeutics and future meta-analysis. Case description: A 46-year-old female patient, with only hypertension previously diagnosed as a medical condition, was admitted to the local tertiary-level hospital, by the general surgery team with the suspicion of possible retroperitoneal cyst. The patient underwent laparotomy and excision of a mass that weighed approximately 2.5 kg, in the analysis performed by the pathology team. It was diagnosed as Primary Retroperitoneal Mucinous Cystadenocarcinoma Grade II with diffuse positive immunohistochemistry "Cytokeratin 7", "Cytokeratin 20" positive focal, "MUC5AC" positive, "CDX2" positive in rare cells. The patient underwent 6 sessions of chemotherapy with Carboplatin and Paclitaxel with decrease of the CA-125 marker and good response to treatment. In the follow-up, after 11 months, the patient presented recurrence with liver metastasis and elevated marker CA-125, which restarted the chemotherapy; however, the patient developed respiratory failure and died at the end of 2017. Final considerations: The PRMC is a rare tumor and still with scarce literature to help the medical team to understand the risk factors, tumor staging and appropriate adequate treatment that decreases the chance of recurrence. This case will help in diagnosis and treatments in the future.