[Persistent polyclonal B-cell lymphocytosis: study of 35 cases]

Background and objectives: Persistent polyclonal B-cell lymphocytosis (PPBL) is a rare entity, presenting especially in adult smoker women. It is characterized by an increase of serum IgM, DR7-HLA haplotype, cytogenetic abnormalities and multiple IgH/BCL-2 rearrangements. To date, it has not been elucidated whether this is a benign or premalignant disorder. We analyzed the PPBL characteristics with especial attention to its evolution.

Patients and methods: Thirty-five PPBL patients from 5 hospitals in Catalonia were retrospectively analyzed. A simultaneous morphologic review of the blood smears was performed by members of the GCCH in a 16 multiple-observer optic microscope. Clinical and biological data were also analyzed.

Results: PPBL presents in the majority of cases with persistent polyclonal B-cell lymphocytosis and affects primarily smoker women. The morphologic hallmark, in absence of viral infections, is the presence of activated lymphocytes with bilobulated and/or cleaved nuclei, and nuclear pockets in the ultrastructural study. Increased serum IgM, HLA-DR7 haplotype, chromosomal abnormalities such as i(3)(q10) and multiple IgH/BCL-2 rearrangements were detected. Thirty-four out of 35 patients are alive after a median follow up of 70.7 months. One patient died because of lung adenocarcinoma and another developed a follicular lymphoma without relation to PPBL.

Conclusions: PPBL has an asymptomatic and stable evolution, although it frequently presents genetic abnormalities. It remains unknown whether it is a premalignant entity, similar to monoclonal gammopathies of unknown significance. Hence, accurate cytologic diagnosis and follow-up are essential.