Which of the following skin disease has a different pathogenesis from the others listed?

A.is Pityriasis rosea           B.is Pemphigus vulgaris C.is Vitiligo                           D.is Bullous penmphigoid Pemphigus vulgaris, vitiligo, bullous pemphigoid, and dermatitis herpetiformis are all immunologic diseases. Pityriasis rosea is an eruption that develops in children and young adults in the spring and fall. The cause is unknown, but it is often associated with a recent upper respiratory infection or flu. It first presents as a single, scaly pink plaque on the trunk, called a "herald patch." Days to weeks later, an eruption of rose-colored pap­ules follows the lines of cleavage in a "Christmas tree" distribution. It typically resolves in 4-6 weeks.