RESUMEN
Peritoneal origin serous papillary carcinoma is an uncommon primary malignancy occurring in the abdominal or pelvic peritoneum lining. It is characterized by peritoneal carcinomatosis with massive ascites, uninvolved or minimally involved ovary, and is histologically indistinguishable from ovarian serous tumors. Better recognition of this phenomenon in recent years has contributed to an increasing diagnostic frequency. We describe a rare case of peritoneal origin serous papillary carcinoma with unusual clinical presentations involving a solitary primary tumor originating from the peritoneal lining of the sigmoid colonal mesentery, without pelvic lymph node involvement or distant metastasis. Because of the location and morphological similarity, it was misdiagnosed as an ovarian malignancy. We aim to assist in the diagnosis of this disease with the following case report, thereby improving the management of patients with this condition.