Concurrent Superior Mesenteric and Splenic Vein Thrombosis in a Prothrombin G20210A Carrier: Radiologic Evolution and Resolution on Apixaban.

Splanchnic venous thrombosis (SVT) is an uncommon vascular condition that may occur in association with liver disease, malignancy, or intra-abdominal inflammatory processes. In cases where these conditions are absent, and SVT occurs as a primary disease process, an underlying thrombophilic predisposition should be considered. Concurrent involvement of the superior mesenteric and splenic veins in this context is uncommon and may suggest an inherited prothrombotic tendency. We describe a 76-year-old man with a known heterozygous prothrombin G20210A mutation who presented with several days of abdominal discomfort and was found to have non-occlusive thrombosis of the superior mesenteric vein extending into the splenic vein. Contrast-enhanced computed tomography (CT) confirmed the diagnosis, and a structured evaluation, including positron emission tomography (PET)-CT and comprehensive hypercoagulable testing, excluded malignancy and other acquired causes. Anticoagulation with apixaban was initiated, and follow-up imaging at three months demonstrated complete radiographic resolution. The patient remained clinically stable without bleeding or recurrent thrombosis at six months. This case highlights the importance of systematic etiologic evaluation in non-cirrhotic SVT and illustrates how an inherited thrombophilic predisposition, such as heterozygous prothrombin G20210A mutation, may contribute to thrombosis in the appropriate clinical context.