Unusual Presentation of Treated Colon Cancer with Extramural Venous Invasion: A Case Report.

Introduction: Colon cancer is one of the leading malignancies globally and continues to be one of the most typical causes of cancer-related mortality. The clinical outcome of the disease depends on the primary tumour stage, regional nodal involvement and distant disease dissemination. It often presents with haematogenous spread to the liver at the time of diagnosis. Another factor for increased mortality is the presence of extramural venous invasion. This is exceedingly important as it has significant prognostic significance and helps predict survival.

Case description: A middle-aged female with a recent history of caesarean delivery presented with abdominal pain and occasional constipation, which led to a series of investigations. Initial computed tomography scan showed proximal to mid-transverse colonic tumoural thickening with locoregional lymphadenopathy and solitary distant metastasis in the left hepatic lobe. This was followed by extended right hemicolectomy and hepatic metastasectomy. The patient remained on follow-up and later presented with thrombus formation in the splenoportal circulation. Initially, this was considered a bland thrombus, and the patient was advised a close follow-up. However, the patient was lost to follow and later presented with extensive thrombosis of the portal and splenic veins.

Practical implications: Confident differentiation of the bland versus malignant thrombosis is crucial to ascertain disease stage and appropriate management. Invasive tissue sampling gives a confident diagnosis of benign versus malignant thrombus. However, using a non-invasive imaging modality, we can still distinguish between the two with reasonable certainty.