Pemphigus vulgaris associated with transient acanthosis nigricans like lesion

A patient with pemphigus vulgaris was treated with predonisolone and cyclosporin. At the sites of healing erosions, hyperkeratotic, hyperpigmented plaques developed; they were clinically and histologically similar to acanthosis nigricans. These lesions regressed after a few months. This case and others described in the literature suggest that such dermatoses might be caused by immunologically as well as mechanically mediated epidermal injury.