Narrowband UVB is first-line phototherapy for generalized vitiligo. Which feature of the 311 nm lamp underlies its superiority over broadband UVB?

• A Greater penetration into subcutaneous tissue stimulating fibroblasts
• B Effective stimulation of follicular melanocytes with minimal erythema and no psoralen requirement ✓
• C Maximal erythemogenic effect ensuring higher cumulative dose
• D Direct cytotoxicity against CD8+ T cells through DNA cross-linking

Explanation

The 311 nm narrowband output lies close to the action spectrum for melanocyte stimulation while producing far less erythema than broadband UVB, allowing higher therapeutic doses without psoralen. It stimulates residual follicular melanocytes and modulates local immunity. Psoralens plus UVA is a separate modality, and erythema is a limiting toxicity rather than the therapeutic goal.

Reference: Fitzpatrick's Dermatology, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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