Clonal identity and differences in primary cutaneous B-cell lymphoma occurring at different sites or time points in the same patient.

Primary cutaneous B-cell lymphomas (PCBCL) are rare. Marginal zone lymphomas and follicle center lymphomas (FCL) represent a majority of these cases, and a significant number of cases present with multiple lesions. It is unclear whether multiple lesions in PCBCL represent dissemination of a single clone or multiple new primary lymphomas. In the current study, we analyzed paired samples from 20 PCBCL patients at more than 1 site (16) or at the same site at different time points (4) and 12 patients with benign lymphoid infiltrates to investigate for the presence or absence of a clone, and if present, whether the clones were identical. Both IGH@ and IGK@ rearrangements were tested using the BIOMED-2 protocol. We identified a clone (IGH@ and/or IGK@) in 19 of 20 (95%) PCBCL patients and 2 of 12 (17%) benign lymphoid infiltrate patients. The B-cell clones were proven to be identical in 11 of 20 (55%) PCBCL patients, including 7 of 16(44%) biopsies from patients with 2 different sites and 4 of 4 biopsies (100%) from patients at the same site but different time points. In 4 cases (3 FCL and 1 marginal zone lymphoma), different clones were detected at different sites, suggesting the possibility of a second simultaneous primary lymphoma. Our results indicate that the presence of identical clones is highly suggestive of lymphoma. To our knowledge, this is the first report to investigate the detection of identical clones in 2 distinct biopsies in PCBCL patients. Although the study is small and the results need to be confirmed in a larger study, these findings suggest that a subset of PCBCL at different sites may represent different primary tumors rather than occurrence of a single disease.

Indolent primary cutaneous B-cell lymphoma: experience using systemic rituximab.

BACKGROUND: Optimal treatment of indolent primary cutaneous B-cell lymphoma (CBCL), marginal zone lymphoma, and follicle center lymphoma, presenting as multiple lesions, has yet to be established. Rituximab is a chimeric monoclonal IgG1 antibody directed against the CD20 antigen of B cells. Clinical efficacy of systemic rituximab in CBCL has yet to be established. OBJECTIVE: We sought to assess the efficacy of systemic rituximab in the treatment of CBCL. METHODS: This was a retrospective study of 15 patients with indolent CBCL treated with intravenous rituximab (375 mg/m(2)) as a single agent. Variable maintenance regimen was used in a subset of patients. Responses were categorized as complete response, partial response, stable disease, or progressive disease. The efficacy end points included were objective response rate, time to response, time to progression, and duration of response. RESULTS: Ten patients with follicle center lymphoma and 5 with marginal zone lymphoma were included. The objective response rate was 87% (60% complete response, 27% partial response). All patients with follicle center lymphoma had a response with 80% achieving complete response. Of the patients with marginal zone lymphoma, 3 had a response, one stable disease, and one progressive disease. Median follow-up was 36 months. Median time to response, duration of response, and time to progression was 30 days, 24 months, and 24 months, respectively. LIMITATIONS: The study was limited by the small sample size and retrospective design. CONCLUSIONS: This study, although small, suggests that rituximab is a reasonable first-line treatment option for indolent CBCL with multiple lesions where local treatment is not effective or desirable.

Evaluation of B-cell clonality using the BIOMED-2 PCR method effectively distinguishes cutaneous B-cell lymphoma from benign lymphoid infiltrates.

Primary cutaneous B-cell lymphomas (CBCL) are a diverse group of lymphomas that are limited to the skin at the time of diagnosis. Recently, standardized polymerase chain reaction protocols for immunoglobulin (Ig) rearrangement in nodal malignancies using the BIOMED-2 method have been studied extensively. However, reports of investigations of Ig clonality in CBCL using the BIOMED-2 method have been scant. We hypothesized that clonality detection in CBCL with the BIOMED-2 method could effectively distinguish malignant from benign B-cell-rich infiltrates in the skin. Formalin-fixed tissue samples from 26 patients with CBCL and 23 with benign lymphoid infiltrates were analyzed for Ig clonality using standardized BIOMED-2 polymerase chain reaction protocols. The (14;18) translocation was also assessed. A clone was detected in 22 (85%) of the 26 patients with CBCL [12/15 (80%) marginal zone B-cell lymphoma; 10/11 (91%) follicle center lymphoma] and in 1 (4%) of the 23 patients with benign infiltrates. The (14;18) translocation was present in 3 (12%) of the 26 patients with CBCL [1/15 (7%) marginal zone B-cell lymphoma; 2/11 (18%) follicle center lymphoma]. Our preliminary data indicate that Ig clonality can be detected in formalin-fixed samples of CBCL with meaningful sensitivity (85%) and high specificity (96%) using the BIOMED-2 method. This study forms the basis for further investigating the role of Ig clonality in distinguishing CBCL from benign lymphoid infiltrates that may pose a challenge in morphologic diagnosis.