Derm Cases · Dermatology / Haematology-oncology
OSCE — chronic bathing-trunk rash: mycosis fungoides recognition and CTCL pathway
An 8-minute OSCE station on mycosis fungoides as a CTCL mimic of eczema/psoriasis, patch-plaque-tumour progression, biopsy strategy, staging concepts, skin-directed vs systemic therapy, and Sezary red flags.
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Target exams
NEET-PGINICETUSMLEPLABMRCP
Prompt
An 8-minute OSCE station on mycosis fungoides as a CTCL mimic of eczema/psoriasis, patch-plaque-tumour progression, biopsy strategy, staging concepts, skin-directed vs systemic therapy, and Sezary red flags.
Brief (to candidate)
A 58-year-old man has a 4-year history of pruritic, scaly, poikilodermatous patches in a bathing-trunk distribution that never fully respond to potent topical steroids or phototherapy labelled as “eczema.” New thicker plaques have appeared; no erythroderma. You have 8 minutes to suspect mycosis fungoides, plan diagnosis/staging, and outline stage-based management principles.
[1]Candidate instructions
- Suspect mycosis fungoides (MF) as CTCL’s commonest subtype.
- Describe patch → plaque → tumour progression and classic distribution.
- Plan biopsy (multiple sites; immunoarchitecture) and key work-up.
- Outline TNMB staging concepts at high level.
- Match skin-directed vs systemic therapies to early vs advanced disease (EORTC-style thinking).
- Flag Sezary syndrome / large-cell transformation red flags.
Examiner checklist (mark each domain / 10)
| Domain | Key actions expected |
|---|---|
| Recognition | Chronic treatment-resistant eczematous/psoriasiform patches often in sun-protected bathing-trunk areas; MF is the great mimicker; may take years and multiple biopsies to diagnose[1][4][6] |
| Natural history | Indolent progression patch → plaque → tumour ± erythroderma; early MF often excellent prognosis; advanced stages need systemic care |
| Diagnosis | Multiple skin biopsies from representative lesions; dermatopathology with immunophenotype (classically CD4+ epidermotropic T cells with phenotype abnormalities); clinicopathologic correlation essential; consider TCR clonality supportively not in isolation[3][5] |
| Staging work-up | Full skin exam, lymph node exam, blood (Sezary cells / flow if erythrodermic or advanced suspicion), imaging selected by stage; TNMB staging frames therapy |
| Therapy principles | Early-stage: skin-directed (topical corticosteroids, phototherapy, topical mechlorethamine/retinoids, local radiotherapy); advanced: systemic options (interferon, retinoids/bexarotene, HDAC inhibitors, antibodies, chemotherapy, allo-HSCT selected) per EORTC consensus specialist pathways[2][5] |
| Red flags | Erythroderma + lymphadenopathy + circulating Sezary cells = Sezary syndrome (urgent haemato-oncology); rapid ulcerating tumours → large-cell transformation; opportunistic infection risk with advanced therapy |
| Communication | Explain chronic lymphoma of skin-homing T cells; set expectations for multi-year management and multidisciplinary CTCL clinic |
Model key actions
- Stop labelling chronic bathing-trunk rash as simple eczema — biopsy for MF/CTCL.[4][6]
- Stage with TNMB mindset and start skin-directed therapy for early disease.[2]
- Escalate urgently if erythroderma/Sezary features or tumour-stage transformation.[1][3]
Common errors
- Years of topical steroids without diagnostic re-biopsy of progressive disease.
- Single inadequate biopsy dismissed as “eczema” forever.
- Jumping to multi-agent chemotherapy for early patch-stage MF.
- Missing Sezary syndrome in erythrodermic patients.
- Not examining nodes or full skin surface.
References6ShowHide
- [1]Lee H. Mycosis fungoides and Sézary syndrome. Blood research, 2023.PMID 37105561
- [2]Latzka J, Assaf C, Bagot M, et al. EORTC consensus recommendations for the treatment of mycosis fungoides/Sezary syndrome - Update 2023. European journal of cancer, 2023.PMID 37890355
- [3]Larocca C, Kupper T. Mycosis Fungoides and Sézary Syndrome: An Update. Hematology/oncology clinics of North America, 2019.PMID 30497668
- [4]Sheern C, Levell NJ, Craig PJ, et al. Mycosis fungoides: a review. Clinical and experimental dermatology, 2025.PMID 40721285
- [5]Weiner DM, Rook AH. Cutaneous T-cell Lymphoma. Hematology/oncology clinics of North America, 2024.PMID 39079789
- [6]Dummer R, Vermeer MH, Scarisbrick JJ, et al. Cutaneous T cell lymphoma. Nature Reviews Disease Primers, 2021.PMID 34446710