Immunophenotype analysis of B-CLL lymphoma and immunocytoma.

The differential diagnosis between lymphocytic lymphoma of the B-CLL type and immunocytoma (IC) can be difficult when it is based only upon morphological criteria. With the aim of improving the distinction between these subgroups, frozen sections of lymph nodes or other biopsied tissues from 14 cases of B-CLL and 16 cases of IC were investigated according to immunophenotype. A panel of 13 B cell-associated and 2 T cell-associated monoclonal antibodies was used. All but one of the B-CLL cases were FMC7-, while 14/16 IC cases were FMC7+ (p less than 0.001). The two negative IC cases were both of the lymphoplasmacytic type, claimed to be "more differentiated" than the lymphoplasmacytoid type. We suggest that the cells in these cases are mature enough to have lost their FMC7 positivity, similar to plasma cells. There was also a statistically significant (p less than 0.01) difference, although not as pronounced, for the anti-CD38 antibody (Leu-17, B-CLL: 3/14, IC: 10/16 positive). No significant difference in expression of determinants was found for any of the other antibodies.