B-Lymphoblastic Leukemia With Aberrant Cd5 Expression: Clinicopathologic Features And Outcome In 10 Cases

Objectives: B-acute lymphoblastic leukemia (B-ALL) is a neoplasm of precursor lymphoid cells committed to the B-lineage. Expression of CD5 is rare in B-ALL.Methods: We studied the clinicopathologic, immunophenotypic, and molecular genetic features of 10 cases of B-ALL with aberrant CD5 expression, and compared with CD5- B-ALL.Results: B- ALL with aberrant CD5 expression is rare and predominantly affects men. Patients with CD5+ B- ALL had shorter median overall survival (21 vs 45 months, P = .0003). Expression of CD5 imposed a challenge in the differential diagnoses between B- ALL and other CD5+ B-cell lymphomas with blastic morphology. Dim CD20 and CD45, lack of surface immunoglobulin, expression of CD34 and TdT, negative immunostain for cyclin D1, and absence of t(11; 14)(q13;q32) support a diagnosis of B- ALL.Conclusions: CD5 expression is rare in B-ALL and associated with poor clinical outcome. CD5+ B-ALL represents a distinct entity that needs to be considered in the differential diagnoses of CD5+ B-cell lymphoproliferative disorders.