Prognostic Value of Immunohistochemical T-Cell Marker Loss in Early-Stage Mycosis Fungoides: A Single-Center Cohort Study

Introduction: Mycosis fungoides (MF) is the most common cutaneous T-cell lymphoma, often exhibiting loss of pan-T-cell markers such as CD2, CD3, CD5, and CD7. While these immunophenotypic alterations assist in diagnosis, their prognostic relevance in early-stage MF remains uncertain. This study aimed to determine whether immunohistochemical loss of T-cell markers CD2, CD3, CD5, and CD7 in patients with early-stage mycosis fungoides is associated with overall survival and progression-free survival. Methods: This retrospective included 83 patients with stage IA–IIA MF diagnosed between 2003 and 2012 at a single institution. Immunohistochemical staining of archived biopsy specimens was performed for CD2, CD3, CD5, and CD7. Loss of marker expression was defined as absence in ≥30% of lymphocytes. Clinical and histopathological data were correlated with survival and progression outcomes using Kaplan–Meier curves and log-rank tests. Results: Loss of at least one T-cell marker was identified in 66% of patients, most commonly CD7 (72%), followed by CD5 (11%) and CD2 (11%). No cases showed loss of CD3 expression. CD7 loss was significantly associated with shorter progression-free survival (p < 0.05), but not with overall survival. No significant associations were found between CD2 or CD5 loss and either survival or disease progression. Conclusions: CD7 loss was the only immunohistochemical abnormality significantly associated with earlier disease progression in early-stage MF, suggesting a potential prognostic role. In contrast, loss of CD2 and CD5 did not affect survival or progression, and CD3 was preserved in all cases. These findings highlight the value of incorporating CD7 status into prognostic assessment, although larger studies are needed to confirm its utility.