Primary cutaneous diffuse large B-cell lymphoma: prognostic significance of clinicopathological subtypes.

Classification and subdivision of primary cutaneous diffuse large B-cell lymphoma (PCDLBCL) are a matter of ongoing debate. In this study we assessed the morphologic, immunophenotypic, and clinical features of 30 cases of PCDLBCL identified during a review of all primary cutaneous B-cell lymphomas in the Scotland and Newcastle Lymphoma Group database. We also determined the number of cases harboring t(14;18) using a polymerase chain reaction and primers to the major breakpoint cluster region. The effect on prognosis of a variety of clinical and pathologic factors was assessed for the group of 30 PCDLBCL and the 5-year disease-specific survival (DSS) of this cohort compared with that of 195 cases of stage I diffuse large B-cell lymphoma arising primarily in lymph nodes, also identified from within the Scotland and Newcastle Lymphoma Group database. Location on the leg was the only independent prognostic factor for determining outcome in PCDLBCL (67% 5-year DSS compared with 100% for the upper body; P = 0.0047). The presence of multiple lesions, involvement of more than one body site, and expression or not of CD10, bcl-2, bcl-6, and CD10 and bcl-6, had no effect on survival. Compared with cases arising above the waist, those on the leg were more often female, were of an older age, and had a significantly higher incidence of bcl-2 expression (P = 0.002) as well as the aforementioned poorer prognosis. They also showed more frequent co-expression of CD10 and bcl-6, supporting a follicle center cell origin for some, but this difference was not statistically significant. Although there was no significant difference in the 5-year DSS between the group of PCDLBCL and the cases of stage I nodal diffuse large B-cell lymphoma (88% 5-year DSS vs. 78%; P = 0.06), the latter were generally treated with more aggressive therapy. Moreover, a significant difference in 5-year DSS was seen when the nodal DLBCLs were compared with PCDLBCLs arising above the waist (78% vs. 100% respectively; P = 0.0135). These results support the current EORTC approach of subdividing PCLBCL on the basis of site to produce prognostically relevant groupings.

Primary cutaneous follicular lymphoma: a clinicopathologic and molecular study of 16 cases in support of a distinct entity.

Primary cutaneous B-cell lymphomas displaying a prominent follicular growth pattern are rare and remain poorly defined, particularly in terms of the frequency of detection of t(14;18) and whether or not, as a group, they represent an entity distinct from follicular lymphoma arising in lymph nodes. The morphologic, immunophenotypic, and clinical features of 16 cases of primary cutaneous follicular lymphoma, identified during a review of all PCBCL in the Scotland and Newcastle Lymphoma Group database, were studied and the number of cases harboring t(14;18) assessed by polymerase chain reaction using primers to the major breakpoint cluster region. Comparisons were made with stage I follicular lymphoma arising in lymph nodes and follicular lymphoma secondarily involving the skin. All cases of primary cutaneous follicular lymphoma had undergone thorough staging, including physical examination and CT scans of chest and abdomen, with 15 of 16 cases also having bone marrow aspiration and/or trephine performed. The morphology and immunophenotype of the lesions were similar to that expected in lymph nodes. All cases displayed a follicular architecture complete with follicular dendritic cell networks and comprised an admixture of CD10 and/or bcl-6-positive neoplastic centrocytes and centroblasts with 13 of 16 cases also expressing bcl-2 protein. None harbored t(14;18), a significantly different finding compared with cases of stage I nodal follicular lymphoma (p <0.001) and secondary cutaneous follicular lymphoma (p <0.039). Relapses occurred in five of 15 patients with a median time to first relapse of 20 months (range 1-73 months; mean 27.2 months). These were multiple in two patients and involved extracutaneous sites in two patients. The propensity for relapse was similar to that in a comparative cohort of stage I nodal follicular lymphoma, but the group of primary cutaneous follicular lymphoma were significantly more likely to attain complete remission; all cases of primary cutaneous follicular lymphoma were in complete remission when last seen compared with 49 of 87 patients with stage I nodal follicular lymphoma (p <0.005). No lymphoma-related deaths were encountered in 15 cases with a mean follow-up >60 months (range 5-119 months). These results support the concept of a subtype of follicular lymphoma lacking t(14;18) involving the major breakpoint cluster region, and with a propensity to arise in the skin. Despite a high relapse rate patients with primary cutaneous follicular lymphoma are more likely to achieve complete remission and may ultimately have a more favorable long-term prognosis than those with equivalent nodal disease.