Lichen Planus Colocalized with Vitiligo: Coincidence?

In a study of 100 patients with vitiligo, a skin condition that causes loss of skin color in patches, 9 were found to have coexistent lichen planus (LP), an inflammatory skin condition. Interestingly, some patients with vitiligo developed LP only in areas of depigmentation. Two theories were proposed to explain this phenomenon: the koebnerization theory, which suggests that both diseases are triggered by local trauma, and the actinic damage theory, which suggests that photodamage in areas of vitiliginous skin leads to the development of LP. This theory is supported by patients developing vitiligo months to years before LP, and reports that PUVA therapy has been associated with lichenoid eruptions in vitiliginous skin. A genetic predisposition may also be involved, as two cases occurred in a mother and daughter. The exact pathophysiological mechanism is not well understood, but a better understanding of the relationship between vitiligo and LP could provide insight into these two common skin disorders.