The clinical and histologic features of lifelong reactive perforating collagenosis in a twenty-five year old woman are presented. Experimentally induced lesions showed the expected evolution and regression, although total time for the experimental lesion to develop and regress was shorter than the time necessary for those occurring spontaneously. Therapeutic trials with a wide variety of topical and systemic medications were without benefit, with the exception of tretinoin cream (0.1 percent), which was regularly effective in reducing the total number of lesions present.