Our data showed that in morphologically atypical CLL only a greater unmutated IgVH, CD20 at a higher density and CD38 expression were detected while, when patients were categorized according to immunophenotypic profile, more advanced clinical stages, more frequent FMC7, CD79b, CD49d, CD20 at high density, smIg at intermediate–high density expression were found and CD43 was more frequently undetectable. Here, MS4A1 is linked to B-cell chronic lymphocytic leukemia.