Acne is a common skin disorder and is known to affect about 855 of people atleast once in their life time. Acne occurs due to inflammation of the sebaceous glands which are the oil forming glands on our skin. These glands are large in size over the face and trunk. This is the reason why acne are seen in these areas. Even on the face, acne is most common over forehead and sides of cheeks.
Acne occur when the outlet (duct) of these glands are blocked as a result of dead cells or bacteria. This causes the oily secretions to be extruded into the surrounding area underneath the skin which causes inflammation.
It is a common disorder affecting 8 out of 10 individuals at some point of time.
- Increased sebum production
- Shedding of skin cells or keratinocytes in duct of oil forming glands (sebaceous glands)
- Bacterial infection: P.acnes
- Hormonal changes
- colonisation of sebum producing gland by bacteria
- immune response of the body
- Genetic predisposition
Why do acne occur
Evolutional of acne
- Comedones in midfacial area seen after puberty
- Become inflammatory in 2-3 years
- Predisposition for developing acne decrease by 20-25 years
Why during teenage years
- Androgen is responsible for acne in both genders: It stimulates sebum or oil production. Androgen receptors,in skin, are present in sebaceous glands and outer layer of hair follicle.
- Testosterone binds to keratinocyte or skin cells in sebaceous glands.
- 17- hydrosteriod dehydrogenase : Type II isoform of this enzyme is most active in sebaceous glands. This enzyme converts testosterone to androstenedione, thereby reducing the concentration of testosterone. Individuals deficient in this enzyme develop acne.
- Growth hormone is also acnegenic
- Oestrogens depress sebaceous activity. They decrease the size of sebaceous glands and also depresses its function.
- Mild comedonal acne is most common in teenagers after attaining puberty.
- Inflammatory lesions are seen after 2-3 years of onset of comedones.
- Midfacial area is the most commonly affected.
Types of lesions in acne
- White heads (Closed comedones)
- Black heads (Open comedones)
- Pimples (red papules)
- Pus filled lesions (Pustule)
- Large swelling (Nodule)
- Soft swelling (Cyst)
Sites of acne
Acne, in general, can involve any part of face. It also involves the trunk, shoulders and arms.
- Adolescent acne involves entire, mostly involved cheeks.
- Comedones (black heads and white heads) mostly affects the T-zone ie forehead, nose and chin
- Adult acne: Seen especially in females. It involves the lower part of face. Presence as red papules and nodules around the jaw and in upper part of neck.
Cycle of acne:
Starts as mild comedones (black heads and white heads)
These also suggest that acne is active and require treatment.