Isolated plantar collagenoma not associated with Proteus syndrome.

Isolated plantar cerebriform collagenomas are a relatively rare type of connective tissue nevus. They have been suggested to be pathognomonic of Proteus syndrome. However, their presence is now considered to be a major criterion of Proteus syndrome, but the diagnosis of Proteus syndrome also requires the presence of other minor criteria. We present an unusual case of an acquired plantar cerebriform collagenoma, which is not associated with Proteus syndrome. Collagenomas, or connective tissue nevi of the collagen type, represent a hamartomatous overgrowth of normal collagen. Isolated plantar collagenoma is rare, and most commonly presents in childhood. We report an interesting case of an isolated plantar cerebriform collagenoma in an adult.