[Acute positive Tdt leukemia with megakaryoblastic involvement. Apropos of an observation of an infant].

After observation of a 10 month-old infant hospitalised for acute thrombopenia associated with signs of marked radiological hyperostosis, the initial medullograms showed a rich bone marrow free of blast cells. Subsequent complications of the thrombopenia were anemia, neutropenia and circulating blastosis. Marrow aspirations at various sites were unsuccessful. X-rays showed a worsening of the conditions and the child suffers attacks of intense pain. Ultrastructural cytochemistry and Tdt disclosed by immunofluorescence showed that the majority of blasts possessed Tdt and 2-3% were PPO positive. The presence of these 2 markers may correspond either to the presence of a promegakaryoblastic leukemia with aberrant Tdt, or to the coexistence of 2 types of blasts cells.