Pemphigus Foliaceus Associated with Psoriasis during the Course of Narrow-Band UVB Therapy: A Simple Coincidence?

Although psoriasis and bullous diseases are considered to be completely different disease entities, the literature has reported a few cases of psoriasis associated with bullous diseases, most of which are bullous pemphigoid. In limited cases, pemphigus foliaceus has also been reported in association with psoriasis. In most of them, pemphigus lesions usually developed on an untreated patient with a chronic history of psoriasis. Herein, we report a case of 53-year-old male with a chronic history of psoriasis who first developed generalized erosive lesions after 26 cycles of narrow-band ultraviolet B (NBUVB) therapy. A diagnosis of pemphigus foliaceus was made based on skin biopsy and direct immunofluorescence assay. Pemphigus lesions were well controlled with combination therapy of oral steroid and azathioprine. This is the first case where pemphigus foliaceus co-occurred with psoriasis during NBUVB therapy.