Cardiovascular collapse and McConnell's sign as early manifestations of leucostasis.

A man in his late 70s with chronic myelomonocytic leukaemia presented for evaluation of acute leukaemic transformation and initiation of cytoreductive therapy after being found to have asymptomatic hyperleucocytosis. Within 24 hours, the patient developed vasopressor-refractory shock, severe lactic acidosis and multiorgan failure. Serial echocardiographic assessments revealed interval enlargement of the right ventricle with development of the McConnell's sign, and abdominal CT showed diffuse bowel wall thickening, likely due to ischaemia. CT angiography excluded pulmonary embolism or occlusion of intra-abdominal arteries. Despite aggressive care, the patient died from cardiovascular collapse within 8 hours of the onset of hypotension. An autopsy revealed extensive infiltration of early myeloid cells in pulmonary, myocardial, hepatic and intestinal microvasculature. This case illustrates different mechanisms by which leucostasis causes acute cardiovascular collapse and stresses the emergent nature of this diagnosis.