Acne vulgaris is a common skin disease of young age group especially pubertal age group Disorder of Pilosebaceous gland , incidence of acne decreases with increase age
Eruption is polymorphic , characterised by
Comedones(pathognomic): types of comedones
Local symptoms involve pain , tenderness.
Scar : lesion of acne usually heals with scar.
Pilosebaceous glands are usually occluded by keratinous plug , which result in retention of sebum , as a result of which colonisation of Propionibacterium acnes occur , due to overdistention of pilosebaceous gland they rupture and result in release of proinflamatory chemicals into dermis and stimulate inflammation.
There is also increase production of sebum which is due to increase activity of androgens due to increased activity of 5 α-reductase activity ( converts testosterone to more active form 5α-dihydrotestosterone , which binds to specific receptor in sebaceous gland and result in increase production of sebum.
(To remember the pathogenesis of Acvne Vulgaris you can use pneumonic SKIP- increase sebum production, keratin pearl, inflammation , Propionobacterium acnes)
Site of Predilection
Seen predominantly on the face( cheek, forehead, chin)
Acne can be associated with Polycystic ovarian syndrome, Weight gain , hirsutism , even due to cosmetic use especially oil based cosmetics , even they are associated with drugs like Anabolic steroids, antitubercular drugs, anticonvulsants