Acne Vulgaris is due to involvement of:

Acne vulgaris is a common inflammatory disease of the pilosebaceous glands. It is a self-limited disorder primarily of teenagers and young adults. The permissive factor for the expression of the disease in adolescence is the increase in sebum production by sebaceous glands after pubey. Small cysts, called comedones, form in hair follicles due to blockage of the follicular orifice by retention of keratinous material and sebum. The activity of bacteria (Proprionobacterium acnes) within the comedones releases free fatty acids from sebum, causes inflammation within the cyst, and results in rupture of the cyst wall. An inflammatory foreign-body reaction develops as result of extrusion of oily and keratinous debris from the cyst. The clinical hallmark of acne vulgaris is the comedone, which may be closed (whitehead) or open (blackhead). Comedones are usually accompanied by inflammatory lesions: papules, pustules, or nodules. The earliest lesions seen in adolescence are generally mildly inflamed or non-inflammatory comedones on the forehead. Subsequently, more typical inflammatory lesions develop on the cheeks, nose, and chin. The most common location for acne is the face, but involvement of the chest and back is common. Most disease remains mild and does not lead to scarring. Ref: 1) Harrison's Internal Medicine; Pa 2. Cardinal Manifestations and Presentation of Diseases ; Section 9. Alterations in the Skin ; Chapter 53. Eczema, Psoriasis, Cutaneous Infections, Acne, and Other Common Skin Disorders ; Eczema and Dermatitis. 2) The Treatment of Modern Western Medical Diseases with Chinese Medicine: A Textbook & Clinical Manual by Bob Flaws, Philippe Sionneau.