Recognizing Recurrent Ovarian Endometrioid Carcinoma: A Case of Malignant Sigmoid Serosa Lesion Mimicking a Mesenteric Cyst

Endometrioid carcinoma (EC) of the ovary typically presents in the fifth to sixth decade of life, arising from endometriosis or benign adenofibromas. While commonly metastasizing intraperitoneally, hematogenous spread to distant sites is rare. We present a unique case of recurrent EC manifesting as a malignant sigmoid colon cyst, a clinical rarity. A 43-year-old woman, previously treated for left ovarian EC, presented with abdominal pain and distension. Imaging revealed a mesenteric cyst, but elevated CA-125 levels prompted further investigation. PET-CT scan identified a cystic mass arising from the sigmoid colon. Secondary cytoreductive surgery confirmed recurrent EC without colonic endometriosis. Immunohistochemistry supported the diagnosis of TP-53 mutant EC. This case underscores the importance of considering rare metastatic patterns in ovarian EC. Vigilant surveillance and multimodal diagnostic approaches are crucial for accurate identification and management of recurrent disease.