DOI: 10.1097/rc9.0000000000000766 ISSN: 2210-2612

Gastrointestinal stromal tumor of the round ligament with synchronous colorectal adenocarcinoma and hepatic metastases: a unique case report

Anas Derkaoui, Tarik Deflaoui, Intissar Aissi, Abdelali Guellil, Rachid Jabi, Mohammed Bouziane
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Introduction and importance:

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the digestive tract. While they usually arise in the stomach or small intestine, primary involvement of the hepatic round ligament is exceedingly rare. The synchronous coexistence of such an unusual GIST with colorectal adenocarcinoma (CRC) represents a major diagnostic and therapeutic challenge.

Case presentation:

We report the case of a 66-year-old man admitted with acute intestinal obstruction associated with epigastric pain and abdominal distension. Contrast-enhanced computed tomography revealed two intra-abdominal masses associated with multiple hepatic nodules. Exploratory laparotomy identified a tumor arising from the hepatic round ligament, a necrotic mesenteric mass causing bowel obstruction, and multiple suspicious liver nodules. Surgical management included en bloc resection of the round ligament tumor, biopsies of the mesenteric and hepatic lesions, and a proximal ileostomy. Histopathological examination demonstrated a high-grade spindle-cell GIST of the round ligament, positive for CD117, DOG1, and CD34, with a high Ki-67 proliferation index, confirming its independent mesenchymal lineage. Concurrently, the mesenteric and hepatic lesions corresponded to metastatic, moderately differentiated colorectal adenocarcinoma expressing CK20 and CDX2. Postoperative colonoscopy confirmed a primary sigmoid colonic tumor, establishing an indisputable diagnosis of two completely independent synchronous primary malignancies.

Clinical discussion:

This case highlights the diagnostic complexity of synchronous abdominal malignancies. Imaging findings alone were insufficient to distinguish metastatic dissemination from two separate primary tumors. Rigorous histopathological and immunohistochemical characterization of each suspicious lesion was therefore crucial because therapeutic strategies differ substantially between GIST and metastatic colorectal adenocarcinoma. The rarity of round ligament GISTs further contributes to the originality of this observation.

Conclusion:

Primary GIST of the hepatic round ligament is exceptionally rare. Its synchronous association with metastatic colorectal adenocarcinoma has not been previously reported. This case emphasizes the importance of systematic histological evaluation of atypical lesions and multidisciplinary management to optimize therapeutic decision-making.

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