[Transient neonatal myeloproliferative disorder in the absence of Down syndrome].

Transient neonatal leukemia or transient neonatal myeloproliferative disorder is commonly associated with Down syndrome. It usually resolves spontaneously in 4-5 months. However, 25 % of patients will subsequently develop acute megakaryoblastic leukemia or myelodysplastic syndrome. It has seldom been described without constitutional anomalies and is even less frequent in twins. We present three phenotypically normal patients with this disorder. One of them was diagnosed because he presented blueberry muffin syndrome. Diagnosis was guided by pathological examination of the skin lesions. The other two patients were monochorionic triplets. Their bichorionic sister presented no hematological disorders. Constitutional chromosomal abnormalities were ruled out in all three patients. They received support treatment only without chemotherapy. The clinical course was favorable with disappearance of marrow and peripheral blastosis in 4-5 months. Follow-up of 18 and 19 months has not revealed any hematological disorders. Caution must be exercised before initiating chemotherapy in these patients. We discuss the differential diagnosis with congenital leukemia and the prognostic and therapeutic implications that this entails.