Hair Darkening in Porphyria Cutanea Tarda

In a study from February 2002, researchers reported the rare occurrence of repigmentation in grey hair in two patients with porphyria cutanea tarda, a condition where repigmentation has been observed alongside other clinical settings such as post-inflammatory effects, certain medications, chronic arsenic exposure, and coeliac disease. The exact mechanism behind this repigmentation is not fully understood, but it is thought to involve the activation and mobilization of melanocytes from the outer root sheath to the hair bulb, where they become functional and contribute to hair darkening. The study did not specify the number of people beyond the two cases presented.