Rare Presentation of a Primary Mesenteric Cystadenocarcinoma: Surgical Management

Primary cystadenocarcinoma of the mesentery is an extremely rare malignant cystic epithelial tumor and represents the malignant spectrum of mesenteric mucinous cystic neoplasms. Due to its rarity, fewer than 25 cases have been reported in the literature, and the clinical characteristics, diagnostic features, and optimal management strategies remain poorly defined. Patients usually present with nonspecific symptoms related to mass effect, including abdominal pain, abdominal distension, nausea, vomiting, constipation, or a palpable abdominal mass, often mimicking ovarian or gastrointestinal tumors. Preoperative diagnosis is particularly challenging because radiological findings are not pathognomonic and tumor markers have limited diagnostic value. We report a rare case of primary mesenteric cystadenocarcinoma in a 20-year-old female who presented with progressive abdominal distension, abdominal pain, nausea, vomiting, constipation, and exertional shortness of breath. Clinical examination revealed a large abdominal mass. Contrast-enhanced positron emission tomography–computed tomography demonstrated a large lobulated abdominopelvic mass with internal septations and heterogeneous enhancement, producing significant mass effect including bilateral ureteric dilatation and hydronephrosis. However, the exact origin of the lesion could not be determined preoperatively. Exploratory laparotomy revealed a large cystic mass arising from the mesentery with dense adhesions to the colon. Complete surgical excision was performed without rupture. Histopathological examination confirmed papillary mucinous cystadenocarcinoma of mesenteric origin. This case highlights the diagnostic difficulty associated with mesenteric cystic malignancies and emphasizes that complete surgical excision remains essential for definitive diagnosis and management.