Persistent patches misdiagnosed as eczema for five years

Patch-stage mycosis fungoides (T2aN0M0B0 — Stage IB (patches only)) — UK supraregional CTCL service referral

Learning points

• Diagnostic delay in MF is common — 4–6 years from first symptom to diagnosis is typical. Patch MF is frequently misdiagnosed as eczema or psoriasis.
• Sun-protected sites (buttocks, breasts, inner thighs) are classical for patch MF. Bathing-trunk distribution is a cliché but a useful trigger to re-biopsy.
• Diagnosis requires multiple deep biopsies (epidermotropism, Pautrier microabscesses, atypical cerebriform lymphocytes, CD7 loss on flow) and TCR clonality.
• ISCL/EORTC TNMB staging (Olsen 2007/2011). T1/T2 subdivided into a/b (patch only vs patch + plaque) because patch-only carries materially better prognosis.
• All confirmed CTCL should be referred to a UK supraregional cutaneous lymphoma service for confirmation and treatment planning.
• Early-stage MF-CTCL skin-directed therapy: potent topical steroids, narrowband UVB, PUVA, topical chlormethine for adults with stage IA, IB or IIA disease (NICE TA720). Brentuximab vedotin (TA577) for CD30+ relapsed/refractory; mogamulizumab (TA754) for relapsed/refractory MF/SS.