Spontaneous tumour lysis syndrome in chronic lymphocytic leukaemia: an unanticipated complication of an undiagnosed disease.

Spontaneous tumour lysis syndrome (STLS) is a rare oncological emergency characterised by the spontaneous destruction of tumour cells in the absence of chemotherapy, with the release of large amounts of intracellular ions and metabolic products leading to organ damage and at times death. In chronic lymphocytic leukaemia (CLL), historically, tumour lysis syndrome has been rarely observed owing to low rate of proliferation and slow response to chemotherapy. We report a rare case of STLS in underlying undiagnosed CLL. A man in his 60s presented with vomiting, diarrhoea, breathlessness on exertion and oliguria. Laboratory evaluation revealed a typical constellation of metabolic abnormalities; hyperuricaemia, hyperkalaemia, hyperphosphataemia and hypocalcaemia with acute kidney injury. Peripheral blood examination showed lymphocytosis with smudge cells. Flow cytometry revealed atypical B lymphoid cells positive for CD5, CD19, CD23, CD45 and CD200. Bone marrow studies and lymph node biopsy supported the diagnosis of underlying CLL which was further confirmed by fluorescent in situ hybridisation. With prompt diagnosis, intervention and intensive monitoring, the end-organ damage was successfully prevented. This case report highlights the importance of keeping high index of suspicion for STLS even without a background history of malignancy as this life-threatening condition is potentially salvageable.