Correspondence: Matthias Schmuth, M.D., Department of Dermatology, Anichstrase 35, A-6020 Innsbruck, Austria. Telephone: 43-512504-81472; Fax: 43-512-504-22990; e-mail: matthias.schmuth@uibk.ac.at Received May 15, 2006; accepted July 10, 2006. ©AlphaMed Press 1083-7159/2006/$20.00/0 doi: 10.1634/theoncologist.11-8-955 Because of its characteristic waxing and waning course, lymphomatoid papulosis (LyP) was previously considered a pseudolymphomatous inflammatory process. However the recent World Health Organization–European Organization for Research and Treatment of Cancer (WHO-EORTC) classification grouped LyP among the indolent cutaneous lymphomas [1]. The rationale for classifying LyP as a cutaneous lymphoma is its association with other lymphoproliferative disorders, particularly the progression of LyP into frank lymphoma, that is, Hodgkin’s disease, cutaneous Tcell lymphoma, or anaplastic large cell lymphoma. In their article “Clinical Mimics of Lymphoma,” Brown and Skarin [2] report a rate of progression of LyP to frank lymphoma of 20%–80%. The high variability in these numbers prompted us to reassess the rate of progression in our patient cohort and in cases reported in the literature, in particular because of the therapeutic consequences involved. Although it seems clear that undue aggressive treatment must be avoided, a high advancing rate of the disorder should entail a therapeutic approach aimed at halting the disease process. In contrast, a low rate of progression would be in favor of a “wait and see” approach. A retrospective analysis of our cohort (11 female, 10 male; median age, 47 years; range, 6–77 years) revealed that the absolute frequency of LyP preceding lymphoma was 2 of 21 patients (9.5%) (Table 1). In comparison, absolute frequencies between 5% and 24% have been reported in the literature [3–10] (Table 2). However, rather than calculating the absolute frequency in a given LyP patient cohort, an analysis of the course of the disease indicates that there is a considerably increased risk for progression when LyP is followed up for extended time periods (Table 3). Therefore, the cumulative risk for progression over time may represent a more relevant basis for therapeutic decisions. Yet estimates of the cumulative risk for progression of LyP to lymphoma vary greatly in the literature. For instance, Bekkenk et al. [7] reported cumulative risks in a cohort of 118 LyP patients of 2%, 4%, and 12% at 5, 10, and 15 years after