Primary cutaneous B-cell lymphomas include extranodal marginal zone B-cell lymphoma, follicular lymphoma, large B-cell lymphoma, and, rarely, mantle cell lymphoma. Our purpose in conducting this review was to determine the clinical and behavioral characteristics of primary cutaneous B-cell lymphomas, their relationship to infectious triggers, and therapeutic response. We conducted a retrospective chart review of 23 adult patients presenting to the dermatology clinic at M. D. Anderson Cancer Center with primary cutaneous B-cell lymphoma between January 1999 and May 2003. Primary cutaneous B-cell lymphomas generally present on the head and neck, with the trunk and extremities afflicted to a lesser extent. Patients were found to have serologic evidence of prior infection with Borrelia burgdorferi (n = 10), Helicobacter pylori (n = 5), and Epstein-Barr virus (n = 6). Overall, treatment of primary cutaneous B-cell lymphoma should involve multiple modalities; however, specific treatment aimed at concurrent or suspected infection, particularly B burgdorferi, is a helpful adjunct and may achieve complete remission in a small subset of patients.