Absence of the t(14;18) chromosomal translocation in primary cutaneous B-cell lymphoma

Background The t(14;18)(q32:q21) chromosomal translocation is found in the majority of nodal follicular lymphomas and in a lower percentage of systemi c high-grade diffuse large B-cell lymphomas, The translocation results in t he juxtaposition of the bcl-2 gene on chromosome 18 with the immunoglobulin heavy chain joining region on chromosome 14. Bcl-2 protein prevents apopto sis and the translocation leads to overexpression of a functionally normal Bcl-2 protein that prevents apoptosis of neoplastic cells. Objectives The p urpose of our study was to analyse cases of primary cutaneous B-cell lympho ma (PCBCL) for the presence of the t(14;18) translocation and to correlate the results with Bcl-2 expression and histological subtype. Methods Forty-four cutaneous B-cell lymphoid proliferations (36 PCBCL, four follicular B-cell lymphomas with cutaneous presentation and four reactive B-cell infiltrates) were analysed by polymerase chain reaction amplificatio n and polyacrylamide gel electrophoresis using consensus primers for the jo ining region on the immunoglobulin heavy chain gene in combination with eit her a primer for the major breakpoint region (MBR) or the minor cluster reg ion (mcr) on chromosome 18. Results None of 36 PCBCL analysed demonstrated a t(14;18) translocation; ho wever, three of four systemic follicular B-cell lymphomas presenting in the skin were found to have a translocation in the MBR, which was confirmed by sequence analysis. Correlation with Bcl-2 immunostaining showed that of se ven patients with high-grade cutaneous diffuse large B-cell lymphoma, four were Bcl-2 positive but had no evidence of a t(14;18) translocation. In the five cases classified as primary cutaneous follicle centre cell lymphoma, the neoplastic cells within the germinal centres failed to express Bcl-2. H owever, Bcl-2-positive neoplastic cells were present in all four cases of s ystemic follicular lymphoma, including the case that did not show a t(14;18 ) translocation. In all cases of marginal zone lymphoma the marginal zone l ymphocytes were Bcl-2 positive. Conclusions These findings indicate that the t(14;18) translocation does no t occur in PCBCL; which suggests the involvement of different pathogenetic mechanisms compared with their nodal counterparts. Furthermore, the detecti on of a t(14;18) translocation in cutaneous B-cell lymphoma should suggest the presence of systemic disease, which underlies the need for exhaustive s taging procedures.