Introduction: Mycosis fungoides (MF) is the most common subtype of cutaneous T-cell lymphoma, and the vast majority of cases are CD4+, where CD4+ lymphocytes outnumber CD8+ lymphocytes in affected tissue. The converse, CD8+ MF, is rare, with little known regarding how it differs from CD4+ MF.
Objectives and Methods: We sought to compare demographics, presentation, and treatment outcomes of adult cases of CD8+ and CD4+ MF at our academic center using data obtained from the United States Cutaneous Lymphoma Consortium registry. Statistical analysis was completed using SPSS Statistics, version 28.
Results: The cohorts included 16 and 77 cases, respectively, of which 83.9% were early stage at diagnosis. Mean age at diagnosis, mean duration of follow-up, and demographics including sex, race, and ethnicity were similar between groups. Stage at diagnosis, anatomic location at diagnosis, and number of biopsies to diagnosis were similar between groups. Clinical features at presentation, including hypopigmentation and erythroderma were also similar between groups (0% vs. 3.9%; P=0.99 and 6.3% vs. 3.9%; P=0.54, respectively). On immunohistochemical analysis of diagnostic skin biopsies, CD2, CD5, CD7, CD30, and TCR gamma delta expression were similar between groups. Proportion with positive T-cell receptor clonality on skin biopsy, proportion with large cell transformation, proportion of cases upstaged, highest stage, and overall treatment response were similar between groups.
Conclusions: Overall, we noted few differences between CD8+ and CD4+ MF, suggesting these two disease processes may behave similarly.
