CD5+ low-grade marginal zone B-cell lymphomas with localized presentation.

Marginal zone B-cell lymphomas (MZBCLs) are low-grade lymphomas that characteristically lack CD5 expression. However, rare cases of MZBCL have been described in which the lymphomatous B cells coexpress CD5 (CD5+ MZBCL). In 7 of 9 reported CD5+ MZBCLs, there was evidence of widespread disease. We report four additional cases of CD5+ MZBCL. Three cases were low-grade B-cell lymphomas of mucosa-associated lymphoid tissue (MALT) involving the lungs, the conjunctiva (bilateral), and the uterus. The remaining case represented a monocytoid B-cell lymphoma involving a posterior cervical lymph node. Southern blot hybridization did not show rearrangements of bc11 or bc12 in the three cases analyzed. All four patients had localized disease and normal peripheral blood counts. Staging of bone marrow biopsies from three patients did not show evidence of bone marrow involvement. The remaining patient had bilateral conjunctival lesions that were present for 15 years without progression. These four additional cases of CD5+ MZBCL show that this group of low-grade B-cell lymphomas occasionally may exhibit an atypical phenotype. Furthermore, in this study, the CD5+ MZBCLs were clinically localized at presentation, in contrast to most other reported cases, which have had dissemination to bone marrow or peripheral blood.