Endometriosis with myxoid change simulating mucinous adenocarcinoma and pseudomyxoma peritonei

A case of endometriosis with myxoid change is presented here which raised concern for metastatic adenocarcinoma and pseudomyxoma peritonei. This is the second case similar to the one described previously in the literature. A 51-year-old woman underwent repair for an umbilical hernia. The tissue sections of the hernia specimen contained isolated pools of mucin surrounded focally by cuboidal-type epithelium. Subsequent CT scan of the abdomen and pelvis revealed a large right adenexal mass. These clinicopathologic findings raised strong suspicion for adenocarcinoma and pseudomyxoma peritonei. Intraoperative frozen section of the right ovary showed an endometriotic cyst. She underwent hysterectomy, bilateral salpingoophrectomy, partial omentectomy, and lysis of adhesions. Permanent sections revealed foci of endometriosis in both ovaries and cervix. Pools of acellular mucin were present in the omentum and bladder peritoneum. There was no evidence of malignancy in any of the specimen. The case illustrates that endometriosis with myxoid change can simulate with mucinous adenocarcinoma and pseudomyxoma peritonei.