[Tumour-like extramedullary hematopoiesis in a patient with multiple renal transplantations].

Extramedullary hematopoiesis is reactive or clonal trilineage hematopoiesis presenting outside the bone marrow, and it is typically caused by an underlying neoplastic process. In this report, we present the case of a 58-year-old patient who underwent multiple kidney transplantations. Follow-up imaging revealed a tumour-like mass in the soft tissue near the graft kidney. Biopsy revealed extramedullary hematopoiesis without dysplastic features or blast increase. The patient did not show blood count abnormalities suggestive of bone marrow disease. From a prognostic and therapeutic point of view, the most important is to distinguish extramedullary hematopoiesis from myeloid sarcoma. In myeloid sarcoma, the proportion of myeloid blasts exceeds 20%, and the condition is essentially equivalent to acute myeloid leukemia, requiring appropriate treatment. Extramedullary hematopoiesis, as in the presented case, may be asymptomatic. In this instance, follow-up is recommended. In symptomatic cases however, drug treatment or radiation therapy may also be applied. Orv Hetil. 2026; 167(34): 1365-1369.