Relative frequency of various forms of primary cutaneous lymphomas

Background: Data on the relative frequency of the various forms of primary cutaneous lymphomas (PCLs) are largely limited to European institutions. Objective: Our purpose was to document the relative frequencies of various PCLs seen at 3 US institutions with active cutaneous lymphoma programs and to compare those with the European data. Methods: Included in this study are newly registered patients seen at MCP H ahnemann University, New York University, and the University of California, San Francisco from July 1, 1995 to June 30, 1998. Results: A total of 755 patients were seen. The frequency distribution of t he major diagnostic groups was as follows: mycosis fungoides/Sezary syndrom e, 82.3%; lymphomatoid papulosis, 12.6% (including patients with associated mycosis fungoides/Sezary syndrome); CD30(+) anaplastic large-cell lymphoma , 0.9%; peripheral T-cell lymphomas, 2.9%; B-cell lymphoma, 4.5%. Conclusion: The most striking finding is the much lower relative frequency of primary cutaneous B-cell lymphomas at US institutions (4.5%) versus the approximately 20% reported by European groups. The reason for this differen ce requires further study.