RÉSUMÉ
@#INTRODUCTION: Primary peritoneal carcinoma (PPC) is an uncommon malignancy and is often misdiagnosed as peritoneal carcinomatosis from metastatic gastrointestinal carcinoma and more frequently from ovarian carcinomas due to a common embryonic origin of the ovary and the peritoneum. Its diagnosis is a challenge for clinicians. Herein, we report a rare case of PPC in a 72-year-old woman who was initially suspected with metastatic ovarian malignancy, and emphasizes points that help differentiate PPC from primary ovarian cancer. CASE: This a case of a 72-year-old female with abdominal discomfort and distension, initially diagnosed with ovarian carcinoma, with abdominal CT scan revealing thickening of the omentum multiple enhancing nodules in the left adnexa, within the pouch of Douglas and subdiaphragmatic region compatible with malignancy such as metastases from carcinoma. Cancer antigen (CA) 125 (3476 u/mL) and CA 15-3 (45.94 u/mL) were elevated. The patient underwent dilation and curettage and diagnostic laparoscopy and biopsy with frozen section, which revealed metastatic clear cell adenocarcinoma, favoring primary ovarian carcinoma. The patient then underwent exploratory laparotomy, total abdominal hysterectomy, bilateral salpingo-oophorectomy with bilateral lymph node dissection, and omentectomy. Further histopathological findings later confirmed that the patient had carcinoma primarily from the peritoneum instead of from the ovary. The patient was discharged, improved and underwent chemotherapy post-operation. CONCLUSION: This report emphasizes how to distinguish primary malignancy from the peritoneum from that in the ovary, preventing misdiagnosis. The emphasis in considering primary peritoneal cancer as a differential diagnosis in patients with abdominal symptoms suspected due to malignancy should be noted.