Derm Cases · Dermatology / Therapeutics / Photomedicine
OSCE — prescribe phototherapy safely: nbUVB vs PUVA, indications, and contraindications
An 8-minute OSCE station on choosing narrowband UVB versus PUVA, first-line use in psoriasis/vitiligo/eczema, pregnancy safety differences, cumulative SCC risk with PUVA, and absolute contraindications including lupus and xeroderma pigmentosum.
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NEET-PGINICETUSMLEPLABMRCP
Prompt
An 8-minute OSCE station on choosing narrowband UVB versus PUVA, first-line use in psoriasis/vitiligo/eczema, pregnancy safety differences, cumulative SCC risk with PUVA, and absolute contraindications including lupus and xeroderma pigmentosum.
Brief (to candidate)
A 32-year-old pregnant woman with extensive plaque psoriasis and a second patient with long-standing vitiligo ask about “light treatment.” The psoriasis patient is on no systemic drugs; the vitiligo patient had many past PUVA sessions. You have 8 minutes to choose modalities, schedule, safety screening, and long-term cancer counselling.
[6]Candidate instructions
- Name nbUVB (311–313 nm) as first-line phototherapy for many inflammatory indications.
- Contrast nbUVB with PUVA (potency, depth, pregnancy, cancer risk).
- State frequency (typically 2–3×/week) and practical shielding.
- List absolute/relative contraindications (lupus, XP, photosensitisers, pregnancy for PUVA).
- Counsel on cumulative PUVA skin-cancer risk.
Examiner checklist (mark each domain / 10)
| Domain | Key actions expected |
|---|---|
| Modalities | Narrowband UVB ~311–313 nm first-line for psoriasis, AD, vitiligo; PUVA = psoralen + UVA (deeper, more potent); excimer 308 nm for localised disease; UVA1 for selected dermal diseases (e.g. morphea/mastocytosis context)[1][2] |
| Pregnancy | Prefer nbUVB (safe in pregnancy/children); PUVA contraindicated in pregnancy (psoralen teratogenicity concerns)[1] |
| Schedule / logistics | Usually 2–3 sessions/week; dose titration protocols; eye protection for patient and staff; genital shielding; medication review each course for photosensitisers[1] |
| Efficacy frame | nbUVB effective in psoriasis and preferred over PUVA for many vitiligo courses when comparable; individualise if prior non-response[2][3] |
| Cancer risk | Cumulative PUVA (especially high session counts, e.g. beyond ~200) markedly raises SCC risk; track lifetime dose; caution combining with ciclosporin[4] |
| Contraindications | Lupus (may flare), xeroderma pigmentosum, Gorlin syndrome often absolute; photosensitising drugs → burn risk; genitals unprotected → burn/cancer risk |
| Communication | Explain delayed response (weeks), need for adherence, erythema as dose-limiting, annual skin checks if high cumulative UV |
Model key actions
- Start nbUVB for pregnant extensive psoriasis; avoid PUVA in pregnancy.[1][2]
- Screen medications and autoimmune photosensitivity before any UV course.[1]
- Document cumulative PUVA exposure and counsel on SCC risk.[4]
Common errors
- Offering PUVA as first-line in pregnancy.
- No genital/eye shielding counselling.
- Ignoring photosensitising drugs (e.g. some antibiotics, thiazides).
- Treating lupus or XP with phototherapy.
- No plan for cumulative dose tracking or skin-cancer surveillance after many PUVA sessions.
References6ShowHide
- [1]Kurz B, Berneburg M, Bäumler W, et al. Phototherapy: Theory and practice. Journal der Deutschen Dermatologischen Gesellschaft = Journal of the German Society of Dermatology : JDDG, 2023.PMID 37485907
- [2]Armstrong AW, Read C. Pathophysiology, Clinical Presentation, and Treatment of Psoriasis: A Review. JAMA, 2020.PMID 32427307
- [3]Yones SS, Palmer RA, Garibaldinos TM, Hawk JLM. Randomized double-blind trial of treatment of vitiligo: efficacy of psoralen-UV-A therapy vs narrowband UV-B therapy. Archives of Dermatology, 2007.PMID 17519217
- [4]Stern RS, Lunder EJ. Risk of squamous cell carcinoma and methoxsalen (psoralen) and UV-A radiation (PUVA). A prospective study. Archives of Dermatology, 1998.PMID 9875197
- [5]Ronen S, Ramot Y, Zlotogorski A, et al. Efficacy of ultraviolet A1 phototherapy for inflammatory, sclerotic and neoplastic dermatological diseases: A 10-year tertiary referral center experience Photodermatol Photoimmunol Photomed, 2023.PMID 36052749
- [6]McNeely W, Goa KL. 5-Methoxypsoralen. A review of its effects in psoriasis and vitiligo Drugs, 1998.PMID 9806110