Acute leukemia in infancy is rare and characterized by a poor outcome [1]. The organomegaly associated with AML 7, in this case of the kidneys, initially misled us towards the diagnosis of a kidney malformation.
A 5 week-old girl was admitted to our department of Onco-Hematology in poor health with pallor, jaundice, and enlargement of the liver and the spleen. Palpable bulky masses were also present in the left and right hypochondria that echography showed to be due to large kidneys. Laboratory studies revealed anemia (Hb: 5.5 g/dL), thrombocytopenia (platelets: 54 G/L) and signs of cholestasis (hyperbilirubinemia: 79 mmol/L, and elevated g GT: 486 UI/L). The stools were pale and urine dark brown. Magnetic resonance imaging (MRI) con-®rmed enlargement of both kidneys. They were irregular and showed multiple cystic cavities (Fig. 1). The hepatic parenchyma was heterogeneous. Therefore polycystic disease of the kidneys with portal ®brosis was suspected.
The nucleated blood cell count was 13.3 G/L, 17% blasts (megakaryoblastic-like), immature granulocytes (3%) erythroblasts (6%) and dystrophic platelets (anisocytosis, large platelets, micromegakaryocytes) were identi®ed on the stained blood smear. The infant was transfered 48 hr later to the intensive care unit because of hematemesis. The clinical status worsened. Enlargement of the spleen, liver and kidneys increased and ascites appeared. Anemia (Hb: 7.5 g/dL) and thrombocytopenia (24 G/L) got worse as well. A bone marrow aspirate showed heavy blastic in®ltration consistent with megakaryoblasts because of cytoplasmic expansions (Fig. 2). Micromegakaryocytes and numerous platelets abnormalities were also found. Only 1% of blasts were peroxydase positive. Most of the blasts reacted with monoclonal antibody to CD 41 (platelet glycoprotein IIbIIIa)(Dako 1 ) con®rming the diagnosis of megakaryoblastic acute leukemia (AML 7 in the F.A.B classi®cation). Blood cytogenetic study revealed a complex chromosomal rearrangement: t(1; 14; 22), a variant of t(1; 22) speci®cally associated with AML 7. No chemotherapy was initiated because of the patient's age. Corticosteroids were started, but she worsened and died 20 days after admission. Autopsy showed blastic in®ltration of the liver, kidneys, and adrenal glands (Figs. 3±4). Immunochemistry with a anti-CD 41 antibody (Dako 1 ) showed positive staining of the large blasts obstructing the liver blood vessels.
AML-M7 is reported in 10% of pediatric AML cases [1]. It is associated with the translocation (1;22) espe-ÐÐÐÐÐÐ