Auftreten eines bullösen Pemphigoids unter UVA-Therapie bei einem Patienten mit Psoriasis vulgaris

A 74-years-old male suffering from psoriasis vulgaris since childhood was treated by external therapy with ointments only until recently. After his very first treatment with UVA light the patient developed bullae, which were characterized clinically, histologically, serologically and immunohistologically to represent bullous pemphigoid. In the disease history of this patient there was no bullous dermatosis before. When treated internally with corticosteroids and azathioprine the bullae regressed. However, after dose reduction the psoriasis relapsed severely as an erythrodermia. During the successful external treatment of the psoriasis and after withdrawing the internal steroid medication, again a disseminated eruption of bullae became evident which was treated immunosuppressively by a combination of prednisolone and azathioprine. An immediate cessation of bullae formation could be induced whenever PUVA treatment was given again. During 7 months no relapse of the bullous pemphigoid was reported under a very cautious dose reduction of the immunosuppressive regimen. An exacerbation of psoriasis vulgaris could be treated by UVA light without pemphigoid eruptions. The induction of a sub-clinically preexisting bullous pemphigoid with autoimmune phenomena under UVA/PUVA treatment as well as the therapeutical strategies for the co-existing psoriasis vulgaris are discussed.