Circumscribed storiform collagenoma, an unusual tumor.

Circumscribed storiform collagenoma is a rare benign tumor. It appears as an isolated skin lesion or as part of the clinical spectrum of Cowden syndrome. The pathogenesis is still controversial. Although its clinical expression is heterogeneous, it has a characteristic histological pattern. We describe a case of a solitary circumscribed storiform collagenoma not associated with Cowden syndrome.