RESUMEN
Tumour lysis syndrome (TLS) is a rare oncological emergency in solid tumours. Because it is associated with bad short-term prognosis, early recognition and treatment are mandatory. This case refers to a middle-aged woman who presented with stage IV colon cancer, with massive hepatic involvement. After three cycles of first-line FOLFOX (folinic acid, 5-fluorouracil and oxaliplatin), she developed acute kidney injury and hyperkalaemia that did not respond to standard measures. High suspicion of TLS prompted further corroborating investigations and early intensive care unit admission. With vigorous hydration and allopurinol, TLS completely resolved and the patient was discharged. Prophylaxis of subsequent TLS recurrence was complicated by biopsy-proven neutrophilic vasculitis secondary to allopurinol. Prevention of TLS with hydration and rasburicase was performed prior to each subsequent cycle of chemotherapy. This case report is intended to highlight risk factors for TLS in solid tumours and focus on treatment and secondary prophylaxis of TLS.