Pemphigus vulgaris on an old surgical scar: Koebner's phenomenon?

Pemphigus is an autoimmune bullous skin disorder. Several cases have been reported to originate in traumatized areas or on a scar, suggesting Koebner's phenomenon. Pemphigus can either remain localized or subsequently extend. This paper reports on a 60-year-old man in whom pemphigus vulgaris began on a 40-year-old surgical scar. The pemphigus initially remained localized to the scar and subsequently extended after two months. The time to onset of this bullous disease on the scar was especially long, compared to that which has been previously reported in the literature. A few cases have been reported where pemphigus developed a few months to a few years after surgery. A time to onset exceeding 3 years is extremely rare.