Provocation of porphyria cutanea tarda by KUVA-therapy of vitiligo.

Therapy with khellin and UVA irradiation (KUVA) is a therapeutic approach to vitiligo. Little is known about the photobiological properties of khellin and its long-term side-effects after prolonged administration. A 47-year-old woman suffering from acral vitiligo since the age of 3 is reported, who developed blisters on hands and fingers during KUVA-therapy. Laboratory findings were consistent with hereditary porphyria cutanea tarda. Electron microscopic examination of a blister revealed clefting below the basement membrane. It is proposed that khellin in some way provoked the porphyria cutanea tarda in this patient.