Nucleolar positivity for CD20: a diagnostic aid in neoplasms of T-cell lineage?

During a period of 5 years (1998-2002), 125 lymphoma cases consisting of 78 non-Hodgkin's lymphoma (NHL), 38 Hodgkin's disease (HD) and 9 NHL/HD were diagnosed by fine needle aspiration (FNA) cytology. In FNA smears of NHL, the 2 most commonly used antibodies for immunocytochemical staining were CD3 (29 cases) and CD20 (33 cases). A case was considered positive if > or = 50% of cells showed a positive reaction.

Of the 78 NHL cases, 33 stained for CD20. Thirty were successfully stained; of these, 26 were positive. Twenty-nine cases stained for CD3. Twenty-five were successfully stained; of these, 3, consisting of 2 lymphoblastic lymphomas and 1 large cell lymphoma, showed a positive reaction. CD20 staining performed on 1 of these lymphoblastic lymphomas and the large cell lymphoma showed a diffuse cytoplasmic reaction, respectively, in 2% and 0% only but positive staining of the nucleoli in 96% and 84% of cells, respectively. Another lymphoblastic lymphoma case, which did not have an adequate number of CD3-positive cells to label it as of T-cell lineage also showed CD20 positive nucleoli in 60% of cells and a diffuse cytoplasmic reaction for CD 20 in 5% of cells.

If our observation is corroborated by other studies, CD20 nucleolar positivity may serve as a diagnostic aid in T-cell neoplasms.