Koebner phenomenon in pemphigus vulgaris patients

KP: Koebner phenomenon PV: pemphigus vulgaris INTRODUCTION Pemphigus vulgaris (PV) is a rare autoimmune mucocutaneous blistering disease characterized by epidermal acantholysis, flaccid bullae, and erosive lesions in the skin and mucosa. The Koebner phenomenon (KP) is defined as the appearance of new, typical skin lesions on areas of injury in otherwise healthy skin. KP is described in several skin disorders, including psoriasis and lichen planus, but it remains questionable in PV. It is important to differentiate KP from Nikolsky’s sign. Nikolsky’s sign is defined as the appearance of bullous lesions on normal-appearing skin immediately after lateral pressure is applied to the skin. In contrast, for the appearance of new blisters at the trauma site to be characterized as KP, there should be a lag time between the trauma and the blister formation. KP is rarely reported in pemphigus, either because of its low incidence in this disease or the rarity of the disease itself. Here we report 2 cases of PV presenting at the site of physical trauma due to KP.