Clinicopathologic significance of loss of CD19 expression in diffuse large B-cell lymphoma.

To clarify the clinicopathologic significance of a loss of CD19 expression in diffuse large B-cell lymphoma (DLBCL), we evaluated CD19 expression immunohistochemically in frozen sections from 227 patients who had received diagnoses of DLBCL according to the World Health Organization classification between 1987 and 2002. Histopathologic features of patients with CD19- DLBCL were reviewed, and their clinical features, immunophenotypes, and prognoses were compared retrospectively with respect to CD19 expression. CD19 expression was positive in 205 patients (90%). The 22 patients with CD19- DLBCL had a median age of 63 years, and the male-female ratio was 11:11. Compared with patients with CD19+ DLBCL, those with CD19- DLBCL more frequently showed elevated lactate dehydrogenase (LDH) levels (73%, P= .011). Morphologically, 15 (79%) of the 19 CD19- DLBCL patients examined showed plasmablastic/plasmacytoid differentiation. Patients with CD19- DLBCL expressed BCL2 protein less frequently than CD19+ DLBCL (P= .042). Especially noteworthy is that half of the patients with CD19- DLBCL died within 2 years after diagnosis. The CD19- DLBCL group showed a survival curve significantly inferior to that for the CD19+ group (P= .034, generalized Wilcoxon test). Our findings demonstrate that loss of CD19 expression in DLBCL is associated with elevated serum LDH levels and a poor prognosis, especially during the early follow-up period.