Rare Absence of CD79alpha in B-ALLs is not Associated with Altered Prognosis

The diagnosis of B-cell acute lymphoblastic leukemia (B-ALL) on the basis of the World Health Organization (WHO) recommendations in 2016 requires the expression of CD19 with CD79a (CD79a), cCD22 and CD10. CD79a is an integral B cell antigen expressed at all stages. Its absence in B-ALL has only been rarely reported. In this study, we described three cases of B-ALL showing complete loss or extremely weak expression of CD79a.

Seventy-five patients with B-ALL diagnosed by flow cytometry over a period of 3.5 years were taken out from the records. Cases lacking for CD79a by flow cytometry were further analysed.

Out of 75 cases, CD 79a negativity was seen in 4% (3/75). However, every three cases expressed other B cell markers. No aberrant expression of myeloid and lymphoid antigens was seen in any of these three cases. The prognosis of these three cases was similar to CD79a positive cases.

Rarely, B cell ALL may lack CD79a. Thus, to avoid the misdiagnosis, a comprehensive antibody panel should be used. There was no prognostic impact of CD79a negativity in this study, however larger studies are needed to confirm these results.