Abnormally expanded pro-B hematogones associated with congenital cytomegalovirus infection.

Hematogones are nonleukemic immature lymphocytes that display a B-precursor phenotype and populate the pediatric bone marrow. We present the case of a newborn with an atypical, marked expansion of hematogones similar to the pro-B cells of infant acute lymphoblastic leukemia, which demonstrated their nonleukemic nature through gene rearrangement analysis and were associated with a congenital cytomegalovirus infection.