We report a patient developing mast cell leukaemia with subsequent multi-organ failure, three years after allogeneic haematopoietic stem cell transplantation for myelodysplastic syndrome. Mast cell leukaemia is a very rare condition, accounting for <1% of all mastocytosis. In this article, we will discuss the atypical disease progression and treatment response, and diagnostic challenges.

(BELG J HEMATOL 2023;14(6):255–8)