Neoplastic cells do not carry bcl2-JH rearrangements detected in a subset of primary cutaneous follicle center B-cell lymphomas.

Whether primary cutaneous follicular lymphoma (PCFL) may or not represent a cutaneous equivalent to nodal follicular lymphoma (FL) is not determined. We have therefore investigated a series of PCFL to determine if tumoral cells carry or not the t(14;18)(q32;q21) translocation, a cytogenetic hallmark of nodal FL. Thirty cases of PFCL were selected according to the criteria of both the European Organisation for Research and Treatment of Cancer and the World Health Organization with 21 cases classified as grade 1 or 2 and 9 cases as grade 3. First, cutaneous tumors were studied by PCR for the amplification of bcl-2/JH rearrangements and by interphase fluorescence in situ hybridization using a dual color probe spanning t(14;18) breakpoints. Second, we tried to determine the origin of bcl2-JH-positive cells by a parallel bcl2-JH and immunoglobulin heavy chain gene amplification of blood mononuclear cells DNA and of DNA extracted from single microdissected B cells. Bcl2-JH rearrangements were amplified by PCR in skin of 9 of 30 (30%) patients with a similar-sized bcl2-JH rearrangement detected in the blood of 7 of these 9 cases. No t(14;18) breakpoint was detected by interphase fluorescence in situ hybridization analysis of 11 bcl2-JH-negative and 5 bcl2-JH-positive PCFL in contrast with its detection in the secondary cutaneous FL and in the nodal FL cases. Single-cell/multigene analysis showed that no single monoclonal B cells of PCFL carried the bcl2-JH rearrangement. Bystander or nontumoral t(14;18)+ B cells emigrating from blood may account for the detection of bcl2-JH rearrangements within PCFL material. Our study also underlines the diagnostic value of interphase fluorescence in situ hybridization to discriminate between t(14;18)-negative PCFL and extracutaneous FL involving the skin.

A comparative analysis of FISH, RT-PCR, PCR, and immunohistochemistry for the diagnosis of mantle cell lymphomas.

Mantle cell lymphoma (MCL) diagnosis first relies on morphology and phenotype that may overlap with other B-cell lymphomas. Therefore, the demonstration of t(11;14)(q13;q32), the cytogenetic hallmark of MCL, is considered of diagnostic value. By studying a series of 35 MCL with characteristic morphology and phenotype (CD5+, CD10-, CD20+, CD23-), we have evaluated the applicability and the sensitivity of interphase fluorescence in situ hybridization (FISH) for t(11;14) detection and other techniques: (1) polymerase chain reaction (PCR) for amplification of t(11;14) genomic breakpoint, (2) competitive RT-PCR for the detection of cyclin D1 transcripts overexpression, and (3) immunohistochemistry (IHC) for cyclin D1 protein detection. Tissues from different origins were analyzed: lymph nodes (n = 24), spleen (n = 3), digestive biopsy (n = 3), tonsils (n = 3), and skin (n = 2). Interphase FISH was performed either on touch preparations (n = 11) and frozen (n = 9) or paraffin sections (n = 15). FISH analysis detected t(11;14) in 34/35 cases (97%) and demonstrated a recurrent CCND1 amplification in t(11;14)+ nuclei of the three blastoid MCL variants of our series. Genomic PCR analysis, hampered by the scattering of 11q13 breakpoints, was positive in only 13/35 cases (37%). RT-PCR analysis was applicable on nonepithelial tissues (27/35) and showed cyclin D1 transcript overexpression in all tested cases (27/35). IHC for cyclin D1 protein was performed either on frozen (n = 12) or on paraffin sections (n = 23), and its sensitivity was higher on paraffin sections (91%) than on frozen sections (25%). A cyclin D1 protein immunoreactivity was observed in 24/35 cases (69%). Our study emphasizes on the use of FISH analysis for the direct detection of t(11;14) because its applicability and sensitivity largely exceeded those of other techniques. It may also provide some informations on secondary cytogenetic changes of potential clinical relevance.