What are the key clinical features that differentiate Mycosis Fungoides from other skin conditions in primary care?

Mycosis Fungoides (MF) is differentiated from other common skin conditions in primary care by its characteristic clinical features, which include persistent, slowly progressive patches or plaques that often have a distinctive poikilodermatous appearance with areas of hypopigmentation, hyperpigmentation, scaling, and atrophy.

Unlike typical fungal infections or eczema, MF lesions are usually non-responsive to standard topical treatments and may present with a chronic course over months to years.

Key distinguishing features include the presence of well-demarcated, often asymmetrical patches or plaques that may be mildly itchy but are typically not acutely inflamed or infected, contrasting with the more inflammatory or exudative presentations of fungal infections or psoriasis NICE CKS.

Additionally, MF lesions often localize to sun-protected areas such as the buttocks, groin, and trunk, which is less common in other dermatoses seen in primary care NICE CKS.

Early MF can mimic benign dermatoses like eczema or psoriasis, but the lack of response to conventional therapies and the chronicity should raise suspicion.

Histopathological confirmation is essential, but clinically, the presence of patches with fine scaling, slight atrophy, and a tendency to coalesce over time, combined with a lack of systemic symptoms, helps differentiate MF from other skin conditions NICE CKS.

Recent literature emphasizes that pediatric and atypical presentations may occur, and a high index of suspicion is necessary when lesions persist despite treatment, especially if accompanied by subtle lymphadenopathy or unusual distribution Colmant et al. 2022.