FLORAL VARIANT OF FOLLICULAR LYMPHOMA - IMMUNOLOGICAL AND MOLECULAR STUDIES SUPPORT A NEOPLASTIC PROCESS

In recent reports of the so-called ''floral variant'' of follicular ly mphoma, an unusual variant of follicular lymphoma mimicking progressiv e transformation of germinal centers, questions have been raised regar ding whether this process represents a malignant lymphoma. We studied 19 examples of the floral variant of follicular lymphoma and report ou r light microscopic, immunohistochemical, and molecular diagnostic fin dings. Morphologic changes consisted of effacement of normal lymph nod e architecture by follicles composed of atypical lymphocytes. The foll icles were surrounded by prominent mantle zones that invaginated irreg ularly into the follicle centers, often imparting a ''floral'' appeara nce. Sufficient material was available for immunophenotypic or genotyp ic studies in 15 biopsies. Twelve of 15 cases studied by immunohistoch emistry demonstrated phenotypes supporting a diagnosis of lymphoma. Fi ve demonstrated light-chain restriction; one was an immunoglobulin-neg ative B-cell neoplasm; and six, in which only formalin-fixed, paraffin -embedded tissue was available, demonstrated overexpression of the bcl -2 protein. Southern blot analysis revealed evidence of clonal immunog lobulin heavy-chain gene rearrangement in all five cases tested. Overa ll, 12 of the 15 biopsies studied with these techniques showed immunol ogic or genotypic support for malignant lymphoma. The results of this study demonstrate that the floral variant of follicular lymphoma does indeed represent a malignant lymphoma.