[Transplantation-associated thrombotic microangiopathy confirmed by renal biopsy].

An eight-year-old girl with myelodysplastic syndrome (refractory cytopenia) received a bone marrow transplant (BMT) from an unrelated donor because of immunosuppressive therapy failure. Following administration of foscarnet for cytomegalovirus reactivation at day40 post-BMT, serum creatinine increased, and proteinuria, hematuria, and hypertension gradually exacerbated and became prolonged. However, neither schistocytosis nor other organ damage was evident. At six months post-BMT, renal biopsy revealed diffuse glomerular damage with glomerular lobulation, a double contour of the glomerular basement membrane, erythrocyte congestion and thrombi in the glomerular endocapillaries, and mesangiolysis, confirming the diagnosis of transplantation-associated thrombotic microangiopathy (TA-TMA). We initiated strict controls regarding fluid balance, salt intake, and blood pressure. The patient's renal function improved 10 months post-BMT. TA-TMA often presents as non-specific symptoms, making diagnosis difficult. In cases of post-transplant renal damage, TA-TMA should be differentiated regardless of whether specific symptoms such as hemolytic anemia and other organ failure are evident, and a renal biopsy should, therefore, be considered.