Rare case of focal mass like perirenal extramedullary haematopoiesis in a renal transplant recipient.

Extramedullary haematopoiesis (EMH) is a physiological process of formation of blood cells outside the bone marrow in response to insufficient production or excessive destruction of blood cells. Most common sites of EMH are liver, spleen, lymph nodes, kidney and paraspinal regions. In this report, we have described a rare case of focal EMH which presented as a mass adjacent to the renal allograft. Imaging characteristics favoured a benign aetiology with MRI signals suggesting the presence of blood and fatty components. The final diagnosis of EMH was made by aspiration cytology and an unnecessary surgery was thus avoided. © BMJ Publishing Group Limited 2020. No commercial re-use. See rights and permissions. Published by BMJ.