Onset of frontal fibrosing alopecia during inhibition of Th1/17 Pathways with ustekinumab.

The mechanism underlying frontal fibrosing alopecia (FFA) is unknown, but proposed mechanisms share commonality of T cell-mediated destruction of the hair follicle bulge. IL-12 and IL-23 are key cytokines involved in CD4 T cell differentiation towards Th1 and Th17 phenotypes. We present a 62-year-old woman who developed persistent FFA while on ustekinumab for treatment of preexisting psoriasis. This case presents evidence against Th1 and Th17 pathways as essential to pathogenesis in FFA. This case also suggests that IL-12 and IL-23 inhibition is ineffective for this form of scarring alopecia.