De-novo CD5 + B- prolymphocytic leukemia (PLL) presenting at younger age with favourable outcome

B-cell prolymphocytic leukemia (B-PLL) comprises 1% of chronic lymphocytic leukemias. CD5 positivity is seen in 1/3rd of cases which generally arise from pre existing CLL. They have longer median survival compared with de novo B-PLL which are commonly CD5 negative and are more aggressive with an older age of presentation. Herewith, we describe a 48-year-old male of de-novo CD5+ B-PLL presenting with minimal lymphadenopathy and massive splenomegaly with 90% atypical lymphoid cells in the peripheral smear and bone marrow. Immunophenotyping was strongly positive for CD5, CD45, CD19, CD22, FMC-7, S-Ig and CD38, moderately positive for CD 11c, weakly positive for CD23 and negative for CD-103 and ZAP 70. The patient responded well to fludarabine and cyclophosphamide and had an uneventful hospital course. Our case illustrates a de-novo B-PLL with aberrant CD5 positivity who had a short duration of illness, younger age at presentation and favourable treatment outcome.