Transient myeloproliferative disorder with a CD7+ and CD56+ myeloid/natural killer cell precursor phenotype in a newborn.

Anewborn with a transient myeloproliferative disorder and a myeloid/natural killer cell leukemia phenotype is described. The blasts expressed CD7, CD33, CD34, CD56, and CD117 but did not react with cytoplasmic myeloperoxidase and were negative for cy CD22, HLA-DR, and CD90 expression. No megakaryoblastic surface markers were identified. The blast population disappeared from the peripheral blood and bone marrow within 2 months, but hepatomegaly and recurrent respiratory insufficiency persisted. The patient died of unilateral pneumonia in the third month of life. Neither extramedullary infiltration nor other hematologic signs of disease progression were found.