Early-stage mycosis fungoides (MF) is diagnostically challenging due to overlap with inflammatory dermatoses. Age-related immunological and cutaneous changes may modify histopathological presentation. We aimed to compare clinical, histopathological and immunophenotypic features of early-stage MF between geriatric and non-geriatric patients.

Multicentre retrospective cross-sectional study.

Dermatology departments of tertiary centres in Türkiye.

A total of 541 patients diagnosed with early-stage MF were included and stratified into geriatric (≥65 years) and non-geriatric (18–64 years) groups.

The primary outcomes were age-related differences in histopathological and immunohistochemical features. Secondary outcomes included clinical characteristics and quality of life measures. Primary endpoints were prespecified a priori (epidermotropism, basilar lymphocytes, epidermal atrophy, dermal lymphocytic infiltration, papillary dermal fibrosis and CD4-dominant versus CD8(+)/CD4(–) phenotypes); all other comparisons were considered exploratory.

The geriatric group had a higher proportion of males (59.5% vs 47.1%; p=0.004), while lesion type, duration, surface involvement and Dermatology Life Quality Index scores did not differ between groups. Histopathologically, epidermotropism (81.3% vs 63.3%), basilar lymphocytes (57.1% vs 45.7%), epidermal atrophy (26.6% vs 13.8%), dermal lymphocytic infiltration (75.8% vs 58.5%) and papillary dermal fibrosis (55.2% vs 38.4%) were more frequent in geriatric patients (all p

Although clinical characteristics were comparable across age groups, geriatric patients showed differences in reported histopathological and immunophenotypic features; these observations may facilitate clinicopathological recognition of early-stage MF in older individuals. However, some features (particularly epidermal atrophy and superficial/papillary fibrosis) are not MF-specific and may partly reflect background age- and site-related changes.