Abstract
Aberrant expression of CD5 has rarely been reported in B cell lineage acute lymphoblastic leukemia (B-ALL). We report the rare immunophenotypic expression of CD5 in a 20-year-old male who was diagnosed to have B-ALL on bone marrow examination. Cytogenetic analysis revealed a mosaic supernumerary marker chromosome. The patient died due to acute pancreatitis after admission. CD5 positive B-ALL may represent a distinct clinicopathologic subcategory of B-ALL with an aggressive clinical course.