A toddler with pallor and recurrent infection

A 2½ year old girl presented to her general practitioner after several weeks of being, in her mother’s words, “tired and just not herself,” preceded by several months of recurrent upper respiratory tract infections. After positive urinalysis, the general practitioner diagnosed a urinary tract infection. Despite repeated treatment with oral antibiotics, she developed four further urinary tract infections over the next two months. At this time—four months after the initial onset of symptoms—the mother noticed her daughter was pale and lethargic. Over the coming few weeks, she also observed the child’s skin become yellow in colour. Eventually, when her daughter rapidly developed fever, night sweats, and joint pain severe enough to prevent walking, the mother made an emergency appointment at her general practice. The toddler was sent urgently to hospital, where examination elicited hepatosplenomegaly and cervical lymphadenopathy. On admission, she was pancytopenic (haemoglobin 28 g/l , white blood cell count 0.89×109/l, platelets 120×109/l). The blood film confirmed pancytopenia, with occasional teardrop cells but no immature lymphoid cells. The working diagnosis was acute leukaemia. ### 1 What other conditions would you include in your differential and why? #### Short answer This child’s initial symptoms were non-specific, although their long duration suggested an underlying disorder such as leukaemia. Recurrent infections suggested immunodeficiency, but as the history unfolded, lethargy and pallor indicated anaemia. The combination of anaemia and jaundice raised the possibility of haemolysis, perhaps, given the infective symptoms, virally induced. Joint pain suggested a septic or juvenile arthritis, but the concurrent anaemia made leukaemia or other malignancy more likely, especially because several joints …