Reactive perforating collagenosis

This uncommon condition was first described by Mehregan, Scwartz and Livingood (1967). It is one of the true perforating disorders where collagen is extruded through the epidermis and it is believed that superficial trauma, in genetically predisposed individuals, leads to this skin response.
Four cases have been studied, three of whom are siblings and the fouth an isolated case.
Routine histopathology, electronmicroscopy and monoclonal antibody studies are described. These techniques are directed to explain the mechanism of this disease which has previously been suggested as due to a primary disorder of dermal collagen. Dermal damage does not induce lesions and a more superficial trauma seems to be the initiating event. Epidermal and dermal factors and inter-relationships are discussed.