Spontaneous tumour lysis syndrome (STLS), occurring before any form of therapy, is a relatively rare phenomenon. Although STLS has been reported in various malignancies, they are particularly common in haematolymphoid malignancies. This letter highlights the morphological clues in the peripheral blood smear and bone marrow that should raise an alert to the possibility of STLS.

Five cases of haematolymphoid malignancies with STLS were included in the study. The clinical and laboratory features of these five cases have been summarised in table 1. Complete haemogram and peripheral smear were available in all these cases. All five patients had anaemia and thrombocytopaenia. cases 1 and 5 developed STLS after hospital admission which was reflected by a sudden and sharp decline in total leucocyte count (TLC) after the onset of STLS. In case 1, the proportion of blasts also dropped from 75% to 30%. Peripheral smear showed degenerating cells with blast fragments in all the cases (figure 1A). Red cell fragmentation and schistocytes were seen in two cases. In addition, in case 3, the automated cell counter showed a spurious increase in platelet count of 93×109/L, whereas on manual counting, it was around 10×109/L. The tumour cell fragments were mistakenly counted as platelets.

Table showing the clinical, haematological and biochemical profile of five cases

(A) (Top left) Peripheral smear showing blasts and their fragments (Leishman×1000). (B) (Top right) Bone marrow imprint with degenerated cells and cellular debris (Leishman×1000). (C) (Bottom left) …