Physical acne
Frictional acne Wilentz and Berger demonstrated that the popularity of the headbands worn by the devotees of the hippie culture produced, in some wearers, an acneiform eruption. This type is comparable to that seen on the necks of concert violinists87 and under the fur headbands worn by people in cold climates. An identical eruption is occasionally seen under tight bra straps.
The mechanism of this type of acne is uncertain: it could represent a hypercornification response to local trauma or the effects of localized hydration on the pilosebaceous duct. Immobility acne Three cases of acne occurring in the perioral region have been observed following prolonged splinting of the teeth after periodontal surgery (MacGregor, Tan and Cunliffe, unpublished observations 1975). Such patients may be unable to take solid food for up to three months. Although the mechanism of this acne is unclear, immobility of the perioral skin is probably an important factor. The acne is usually mild but it is rather distressing to the patient, especially since the dental operation is often performed for cosmetic reasons. The acne usually settles with topical and/or oral therapy 3-12 months after the removal of the splints.