Flow cytometric immunophenotypic studies performed on bone marrow demonstrate predominantly heterogeneous T-lymphoid cells. Admixed are polyclonal B-lymphoid cells and maturing myeloid cells. The large lymphoid cells did not appear to have been characterized by these studies, possibly due to sampling or by the exclusion of the cohesive clusters of cells after filtration.
The cytogenetic studies demonstrate a mosaic abnormal male bone marrow chromosome analysis. There is a normal cell line in addition to a hyperdiploid chromosome pattern with trisomy 5, an abnormal chromosome 15, and an abnormal chromosome 19 (47, XY, +5, add (15) (q22), add (19) (q13.3) , chtb (21) (cen)  / 46,XY  ) (Fig 12).