Significant high expression of CD23 in follicular lymphoma of the inguinal region

Aims: Inguinal lymph nodes are considered to be problematic for the diagnosis of lymphoma due to architectural changes resulting from previous inflammatory processes. The aim was to investigate the morphology and immunophenotype of follicular lymphomas (FL) in order to clarify whether FL presenting in inguinal nodes differs from FL biopsies from other sites. Methods and results: A total of 219 FLs were studied, comprising 78 biopsy specimens of inguinal lymph nodes and 141 from other sites. All samples were assessed for growth pattern, grade, sclerosis and immunophenotype (Bcl-2, CD10, CD23, Mib-1). Cases negative for Bcl-2 were analysed by polymerase chain reaction and fluorescence in situ hybridization. In comparison with the biopsies from other regions, we found a significantly increased number of CD23+ FLs in samples of inguinal lymph nodes (38% versus 21%). Expression of CD23 was more frequently detected in grade 1 FLs than in other grades (grade 1, 37%; grade 2, 18%; grade 3, 23%; transformed, 6%). Other immunohistochemical parameters, however, did not differ between the two groups. Conclusion: There is an unexpectedly high frequency of CD23 expression in FL in general, which is even more pronounced in inguinal nodes.