Aberrant NK cell associated marker (CD56 and CD57) expression in chronic lymphocytic leukemia.

BACKGROUND: Chronic lymphocytic leukemia (CLL) is one of the commonest leukemias that has been reported extensively throughout the literature. The characteristic phenotype includes co-expression of CD5 and CD23, along with dim expression of light chain and CD22/CD79b, with lack of FMC7. The immunophenotypic scoring system given by Matutes has been used to differentiate CLL from non-CLL chronic lymphoproliferative disorders. Various aberrancies have been described in CLL cases, including abnormal (dim or bright) expression of B cell markers and lineage infidel T cell, myelomonocytic, or rarely Natural killer (NK) cells markers. However, the aberrant co-expression of CD56 and CD57 has not yet been reported.

METHOD AND RESULTS: We hereby report a case of 62-year female with a typical CLL phenotype and Matutes score of 5, showing the expression of CD56 and CD57.

CONCLUSION: This entity may represent a rare subtype of CLL which needs to be studied more extensively for its prognostic implications. This is the first report of CLL with aberrant CD56 and CD57 expression.