Clinicopathological and immunophenotypic studies on 12 cases with B cell chronic lymphocytic leukemia

Abstract

To clarify the histogenesis of B cell chronic lymphocytic leukemia (BCLL), clinicopathological and immunophenotypic studies were performed using a large panel of monoclonal antibodies on 12 cases with BCLL including three caes with prolymphocytic/chronic lymphocytic leukemia (CLL/PL). Immunophenotypically, CD19 and CD20 were positive for all cases of this series and CD5, CD21, CD22, CD23, CD25, CD38, Leu‐8, KB‐61, and bcl‐2 protein were expressed in variable proportion from case to case. CD10, however, did not react. No alkaline phosphatase (ALP) positive cases were found. The phenotype of BCLL was similar to that of B cells of the mantle zone (MZ) of secondary follicle in the lymph node. It is therefore postulated that the neoplastic cells of BCLL in these cases might be derived from B cells of the MZ. Moreover, the cells possibly originated from the lymphocytes located in the inner layer of the MZ, since ALP+ B cells are usually observed in the outer layer of the MZ. The pseudofollicular (PF) pattern was observed in four biopsied lymph nodes among five cases tested, but no such a pattern in an aspiration clot of bone marrow. These four cases consisted of three cases with CLL and a case with CLL/PL. The immunohistochemical study showed that there were many proliferating cells showing Ki‐67+ in the PF area of the lymph nodes. In these cases, leukemic cells might have developed from the PF area of the lymph node.

CD5‐negative chronic lymphocytic leukemia: Does this entity really exist?

“…Now, throughout this process of refining the diagnostic criteria for CLL, pseudofollicles were associated with a B-cell chronic lymphoproliferative disease characterized by CD5 + , CD20 dim/neg , CD23 + , CD79b dim/neg , FMC7 dim/neg , and sIg dim (CD81 dim , CD200 + , and ROR1 + were only recently associated with CLL). Yet, it is important to notice that, to our knowledge, there are no large, published studies comparing the presence of pseudofollicles in lymph node or bone marrow biopsies with a complete CLL blood immunophenotypic profile, including modern antigens such as CD81, CD200, and ROR1, although there are studies documenting the presence of pseudofollicles (in lymph node or bone marrow tissue sections) with a relatively limited CLL immunophenotype (Asplund et al, 2002;Bahler et al, 2000;Carbone et al, 1992;Ellison et al, 1989;Garces et al, 2018;Gibson et al, 2011;Giné et al, 2010;Kilo & Dorfman, 1996;Nakamura et al, 1994;Nguyen et al, 1995;Oka et al, 1993;Teixeira Mendes et al, 2017). Therefore, it is possible that many of these cases, identified with a less extensive panel of immunological markers, were not, in fact, bona fide CLL cases.…”