The morphological findings are commonly associated with EBV infection (45% atypical lymphocytes).
This case was chosen because of the classic hematologic findings and the opportuniy to perform flow cytometric studies on this bone marrow aspirate. (Flow cytometry was performed at no charge to the patient and used for educational purposes only.) Although the Epstein Barr virus infects the B-lymphocytes, it results in an expansion of the CD8+ T-lymphocyte population in the peripheral blood. This population of cells also demonstrates increased expression of HLA-DR antigen which is consistent with in vivo activation(Clin exp Immunol 1991;83:447-451). These findings were confirmed in the bone marrow aspirate in this case. We were unable to review the peripheral blood slide from the outside hospital to confirm the presence of blast-like cells.
Contributed by Lisa J. Kohler, MD and Charles A. Richert, MD