A patient with psoriasis fails topical therapy. Narrow-band UVB (NB-UVB) phototherapy is initiated. Compared to broad-band UVB, NB-UVB (311 nm) has which advantage?
- A More selective suppression of psoriatic T-lymphocytes with less sunburn risk (erythemogenic wavelengths 290–300 nm excluded) ✓
- B Deeper dermal penetration allowing sub-epidermal immune modulation
- C Ability to activate psoralens without systemic administration
- D Lower cost and equipment complexity compared to PUVA
Correct answer: A. More selective suppression of psoriatic T-lymphocytes with less sunburn risk (erythemogenic wavelengths 290–300 nm excluded)
Explanation
NB-UVB at 311–313 nm corresponds to the most therapeutically effective wavelength for psoriasis while excluding the highly erythemogenic 290–300 nm range present in BB-UVB. This allows delivery of higher therapeutic doses with reduced burning, lower long-term skin cancer risk compared to PUVA, no need for psoralens, and no risk of PUVA-associated systemic side effects (nausea, phototoxicity, cataract). NB-UVB is now preferred over PUVA for most cases.
Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.