Pseudoepitheliomatous hyperplasia in Mycobacterium ulcerans infection.

Pseudoepitheliomatous hyperplasia of the epidermis occurring with Mycobacterium ulcerans skin infection may result in localization of the infected area with discharge of necrotic material, followed by healing leaving a depressed scar. The process represents more than simple re-epithelization of an ulcerated skin surface; it is a mechanism which produces active extrusion of necrotic material containing viable mycobacteria and should be seen as part of a protective physiological response to the infection.