Renbök Phenomenon in an Alopecia Areata Patient with Psoriasis
A 23-year-old female patient presented in April 2012 with a flare of psoriasis, involving the trunk, extremities and the scalp. She had a similar flare at the age of 13, and also history of patch-type scalp AA, both resolved following topical steroid treatment. Two months later, in June 2012, she experienced localized hair loss on the scalp, concomitantly with complete resolution of the psoriatic plaque in this region. On examination, a 3 cm patch of nonscarring hair loss was observed, and dermoscopic examination revealed perifollicular pigmentation, exclamation hairs and yellow dots, corresponding to AA. Interestingly, the psoriatic plaque engulfed the AA area, but sharply stopped at its border []. The patient was treated topically for her AA with clobetasol propionate, with stabilization of hair loss when the patch reached a size of 5 cm × 6 cm in September 2012. In parallel, the patient had reappearance of psoriatic plaques inside the area of hair loss, which coincided with the presence of terminal hairs localized to these psoriatic plaques [].