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Photolichenoid papules within vitiligo induced by narrowband UVB phototherapy

Editor Vitiligo is a disorder affecting up to 1% of the population and presents clinically as depigmented macules and patches. Narrowband ultraviolet B (nbUVB) phototherapy is a well-recognized and effective treatment for vitiligo. Identifying complications of nbUVB phototherapy of vitiligo is essential for appropriate patient management. Here, we report photolichenoid papules within vitiliginous skin (PLPV) as a complication of nbUVB phototherapy and identify the treatment parameters associated with this complication. Of 127 vitiligo patients receiving nbUVB phototherapy from 2006 to 2013 in the Vitiligo and Pigmentation Clinic of the University of British Columbia, four patients (one male and three females; age range 29–66) with generalized vitiligo developed 2–5 mm sized scaly red papules limited to the vitiliginous skin (Fig. 1a–c). The mean duration of treatment (from first to last phototherapy session, including periodic interruptions) with nbUVB at onset of the papular eruption was 70 months (range 42–82 months). This duration corresponds to an average of 375 treatments (range 220–676) and mean cumulative dose of 149.5 J/cm (range 50.2–288.9 J/ cm). Three patients consented to undergo biopsy, which revealed lichenoid infiltration without atypia in the upper dermis (Fig. 1d–f). The PLPV lesions persisted from 2 to 12 months after discontinuation of nbUVB, and recurred with resumption of nbUVB in two patients. To identify clinical and treatment factors that could be associated with the development of PLPV, a retrospective chart review of all vitiligo patients undergoing nbUVB phototherapy (University of British Columbia Clinical Ethics Review Board, Protocol H13-02110) was performed (Table 1). Data collected included patient demographics, vitiligo clinical features and nbUVB phototherapy parameters. A total of 127 vitiligo patients received nbUVB over the duration specified and four individuals (3.1%) developed PLPV. Based on our patient cohort, the estimated overall 95% confidence interval rate for PLPV is 0.1–6.2%. Logistic regression analysis using a forward stepwise method was performed using SPSS version 22.0 (IBM, Armonk, NY, USA). Age, sex, ethnicity, vitiligo duration, vitiligo type and vitiligo surface area affected were not statistically significant variables associated with development of PLPV. By univariate analysis, nbUVB treatment duration (P < 0.001), number of treatments (P < 0.001) and cumulative dose (P < 0.001) were each identified as significant variables, with prolonged treatment duration having the highest impact. By multivariable analysis, there was only one statistically significant variable; duration of nbUVB treatment was longer for patients who developed PLPV