Köbner Phenomenon in a Rituximab-Treated Pemphigus Patient: Beware Disease Activity

Pemphigus consists of a group of rare autoimmune blistering diseases that are typically characterized by the appearance of intraepithelial blisters on the skin and/or mucosa. Pemphigus vulgaris (PV) and pemphigus foliaceus (PF) are 2 well-known forms of pemphigus. Although they have distinct clinicopathological features, each of these conditions could switch to the other. The Kobner phenomenon (KP) is described as the appearance of new lesions in the uninvolved skin as a consequence of different kinds of trauma. It has been described in several skin disorders, including psoriasis, vitiligo, lichen planus, and rarely pemphigus [1]. Here we report a patient with previously diagnosed mucocutaneous PV who developed PF after rituximab (RTX) therapy and developed crusted lesions some weeks after surgery for femoral avascular necrosis at the surgical site.