Colourectal cancer (CRC) is the fourth most common cause of death from cancer worldwide. While rates for CRC in adults age 50 and older have been declining, incidence rates in young adults, a population routinely not screened, has been increasing. We report a rare case of high-grade CRC in a previously healthy 27-year-old man, presented to us with symptoms of increasing abdominal pain and distension. Extensive diagnostic investigation revealed hepatomegaly with multiple processes, signs of vasculitis, extensive liver necrosis, enlarged retroperitoneal and mesenteric lymph nodes, splenomegaly, ascites and multiple vein thrombosis. The patient passed away shortly after admission due to treatment-resistant tumour lysis syndrome and multiple organ failure. Biopsy results revealed disseminated adenocarcinoma of the colon, with metastases to lymph nodes, liver, lungs and pleura. CRC in younger patients tend to present at a later stage and appears to be more aggressive, with a poorer pathological differentiation.