title: An acne-free naevus.
abstract: Investigation of rare disorders may sometimes help in the understanding of common problems. We describe a patient with an unusual and previously unreported acne-free naevus occurring in an area severely affected by acne. Investigation revealed smaller sebaceous glands, a reduced sebum excretion rate, decreased number of Corynebacterium acnes in the pilosebaceous ducts and a reduced conversion of testosterone to 5 alphadihydrotestosterone in the areas which were free of acne compared with acne-bearing skin. The results of these investigations support some of the suggested mechanisms responsible for the development of acne.
mesh_terms: D000152:Acne Vulgaris / Q000473:pathology* / Q000503:physiopathology; D000293:Adolescent; D006801:Humans; D008055:Lipids / Q000032:analysis; D008297:Male; D012627:Sebaceous Glands / Q000503:physiopathology; D012629:Sebum / Q000378:metabolism; D012867:Skin / Q000382:microbiology / Q000473:pathology*
chemical_list: D008055:Lipids