CLINICAL QUIZ Thrombotic microangiopathy in a pediatric patient: answer Z. Birsin Özçakar & Fatoş Yalçınkaya & Arzu Ensari & Tanıl Kendirli & Mesiha Ekim & Suat Fitöz Received: 5 April 2008 / Revised: 9 June 2008 / Accepted: 11 June 2008 / Published online: 16 October 2008 # IPNA 2008 Keywords Child . Malignant hypertension . Thrombotic microangiopathy . Acute renal failure Answers Thrombotic microangiopathy (TMA) has been used as a unifying term for microvascular thrombosis due to a variety of diseases, including hemolytic uremic syndrome (HUS), thrombotic thrombocytopenic purpura (TTP), hypertension, eclampsia/pre-eclampsia, disseminated intravascular coagu- lation, autoimmune disorders such as systemic lupus erythematosus (SLE) or antiphospholipid antibody syn- drome, and medications [1]. Laboratory characteristics of TMA include hemolytic anemia, thrombocytopenia and elevated serum level of lactate dehydrogenase [2]. When our patient presented with the findings of TMA, severe hypertension and acute renal failure, our initial diagnosis was HUS or a systemic disease such as SLE. We could easily rule out SLE from the clinical and laboratory findings. We also performed a renal biopsy, due to the presence of atypical clinical findings, and it was consistent with TMA. Atypical HUS or TTP, a rare disease in the pediatric age group, seemed to be the most probable diagnoses. However, the presence of severe hypertension, grade IV hypertensive retinopathy and severe left ventric- ular hypertrophy kept us away from these diagnoses. Then we considered malignant hypertension (MH) as the cause of the TMA and acute renal failure in our patient. Recovery of the TMA findings with aggressive control of hypertension justified our diagnosis. The patient was then investigated further for the presence of secondary causes of hypertension. 99mTc- dimercapto-succinic acid (DMSA) scintigraphy showed a small right kidney and nonhomogeneous activity in the lower pole of the right kidney. The left kidney was increased in size, and cortical activity was reduced in the lower pole of the left kidney (Fig. 1). 99mTc-mercapto- acetyl-triglycerin (MAG3) scintigraphy showed a small right kidney with significantly decreased and delayed activity. Findings from voiding cystourethrography and magnetic resonance angiography of the renal arteries were normal. A detailed past history uncovered febrile urinary tract infections on two occasions. The patient was followed up with regular dialysis in the following 5 months. In the second renal biopsy that was performed 5 months later to determine the long-term prognosis, no thrombotic Pediatr Nephrol (2009) 24:1139–1141 DOI 10.1007/s00467-008-0946-3 This article refers to the article that can be found at http://dx.doi.org/ 10.1007/s00467-008-0947-2. Z. B. Özçakar : F. Yalçınkaya : M. Ekim Department of Pediatric Nephrology, Ankara University School of Medicine, Ankara, Turkey A. Ensari Department of Pathology, Ankara University School of Medicine, Ankara, Turkey T. Kendirli Department of Pediatrics, Ankara University School of Medicine, Ankara, Turkey S. Fitöz Department of Radiology, Ankara University School of Medicine, Ankara, Turkey Z. B. Özçakar (*) Fakülteler Mah.Yeni Acun Sok. 11/2, Cebeci, Ankara, Turkey e-mail: zbozcakar@yahoo.com