B cell chronic lymphocytic leukemia with florid reactive CD4+ T cell lymphocytosis in lymph nodes

This case is of an unusual florid reactive CD4+ T Cell lymphocytosis involving lymph node (LN) and overshadowing residual B chronic lymphocytic leukemia (CLL). A 65 year old female with a 9 year history of untreated B-CLL presented with weight loss, splenomegaly and lymphadenopathy. B-CLL was confirmed on the basis of peripheral blood lymphocytosis, bone marrow trephine findings and flow cytometry analysis. However, the LN biopsy showed appearances of a diffuse small lymphocytic population mimicking a leukemic T-cell infiltrate. Immunophenotyping and molecular analysis demonstrated the major cell population to be reactive CD4 positive T lymphocytes.