[Contribution of the analysis of genotype to the diagnosis of malignant lymphoma with abundant epithelioid reaction. Apropos of a case].

The authors describe the case of a 67 year-old woman bearing a malignant lymphoma displaying two different histological patterns: a Lennert's lymphoma pattern in a cervical lymph node and a diffuse centroblastic lymphoma pattern in an axillary node. Immunophenotyping on frozen and paraffin sections showed a predominant positivity of T-cell markers in the cervical node, while the axillary lymphadenopathy exhibited a major positivity of B-cell markers and a restricted expression of the lambda light chain. However, genotyping provided the evidence of a single neoplastic B-cell clone proliferating in both cervical and axillary nodes. These findings suggest that histological pattern of Lennert's lymphoma is devoid of absolute specificity. Thus, genotypic analysis is a useful tool for the diagnosis of so-called "lymphoepithelioid lymphomas".