EXPRESSION OF CD44 (HCAM) IN SMALL LYMPHOCYTIC AND MANTLE CELL LYMPHOMA

Small lymphocytic lymphoma (SLL) and mantle cell lymphoma (MCL) are sm all B-cell lymphomas that share many morphological and immunophenotypi c features, both expressing the T-cell antigen CD5. Because of this, t here is speculation that these two lymphomas may have a common origin, both arising from the mantle zone of the lymph node. CD44 (HCAM), a g lycoprotein ''homing receptor,'' has been reported as a marker of smal l B-cell lymphomas for determining behavior as well as the nodal cell of origin. Intensity of CD44 expression also has been correlated with dissemination of lymphoma. We studied 50 cases with classic features o f SLL (30 cases) or MCL (20 cases). Immunophenotypic analysis was perf ormed on paraffin sections. All cases of MCL and SLL, were CD20 positi ve; CD5 was expressed in 19 of 25 (76%) SLL and 11 of 15 (73%) MCL. Cy clin D1 was expressed in 11 of 17 (76%) MCL and no cases of SLL. CD43 coexpression was seen in 27 of 29 (93%) SLL and 17 of 19 (89%) MCL. CD 23 was positive in 25 of 28 (89%) SLL, and 2 of 20 (10%) MCL. Bcl-2 wa s positive in 18 of 22 (82%) SLL and 15 of 16 (94%) MCL. CD44 was posi tive with moderate to strong intensity in 11 of 30 SLL and 15 of 20 MC L. Peripheral blood involvement did not correlate with CD44 immunoreac tivity. MCL tended to have intense CD44 immunoreactivity, whereas SLL tended to show weaker CD44 intensity. This trend in the intensity of C D44 in MCL suggests that CD44 may be helpful in distinguishing SLL fro m MCL and possibly elucidating the origin of these CD5-positive B-cell neoplasms.