Primary cystadenocarcinoma that arises in the broad ligament is extremely rare, especially when it is mucinous. We report the case of a 59-year-old woman with a cystic mass of the right broad ligament who underwent a complete excision of the mass (7 x 7 x 3 cm) with hysterectomy, right salpingo-oophorectomy, omentectomy, appendicectomy, and peritoneal biopsies. Pathologic examination showed a low-grade cystadenocarcinoma with a mucinous component limited to the broad ligament. Despite the chemotherapy (cisplatinum and cyclophosphamide) performed, early tumor recurrence occurred after approximately 6 months. Our observation revealed an abundant mucin production with pools of mucin similar to those of pseudomyxoma peritonei and an inflammatory infiltrate with prominent lipid phagocytosis. Immunohistochemical analysis demonstrated a strong and diffuse positivity for both cytokeratin 7 and epithelial membrane antigen. A less extensive staining with carcinoembryonic antigen and a focal unequivocal positivity with cytokeratin 20, particularly in mucin-secreting cells, were also observed. This finding could indicate a metaplastic process toward colonic phenotype similar to primary ovarian tumors.