Acne is a common skin disorder of the pilosebaceous units (hair follicles and the sebaceous gland) forming papules (raised solid bumps) and pustules (surface bumps containing pus) on the face, chest and upper torso.

These papules and pustules are formed, as a result of a buildup of dead skin cells, bacteria and dried sebum, blocking the hair follicles in the face, chest, shoulders or back.


Acne is classified into various categories, however below are the most common forms in order of prevalent occurrence. They are as follows:

  • Acne Vulgaris:

Most common form of acne, occurs during puberty and affects the face, back, and chest. It is more common in boys, 30-40% of whom develop acne between the ages of 18 and 19 years. However, in girls, it mostly occurs between 16 and 18 years. Resolving acne vulgaris lesions in adults most often leads to scarring known acne keloidalis nuchae.

  • Acne Excoriee:

A variant of acne, where the patient picks at the skin producing disfiguring erosions. This form of acne is often mild. However, it tends to persist due to patients’ habit of picking the skin.

  • Infantile acne:

Localized acne lesions present on the face of an infant, in the first few months of life. Topical or systemic treatment may be required in this form of acne. However, it normally resolves spontaneously and can last for about 5 years. Scarring can occur in this form of acne and is associated with severe acne in adolescents.

  • Acne Conglobata/Fulminans:

This is a severe form of acne, common in tropical areas and in boys. It is extensive and presents with nodules (deeper, firm bumps containing pus) and cysts (large pockets on the skin containing pus). This form of acne affects the trunk, face, and limbs. It is often associated with systemic symptoms such as malaise (general body discomfort), fever and joint pain.

  • Pyoderma Faciale:

This form of acne occurs on the midface of young women. It may be similar to acne fulminans. It presents with erythematous plaques (reddish flattened bumps) and pustules, involving the chin, cheek, and forehead. Papules and nodules can also develop.


The common triggers involved in acne are as follows:

  • Puberty: During puberty, there is increased production of the male sex hormone (androgen), which stimulates the production of sebum and increases the production of keratinocytes (keratin cells). The increased production directly correlates with an increased probability of hair follicles being blocked by sebum and the cells.
  • Hormonal changes that occur with pregnancy or during menstruation
  • Cosmetics, cleansers, lotions, and clothing (too-tight clothing)
  • Increased humidity and sweating.
  • Some drugs and chemicals (For example, corticosteroids, lithium, phenytoin, and isoniazid) can worsen acne.
  • Polycystic Ovarian Syndrome: A hormone disorder in females that disrupts the menstrual cycle causing or worsening acne formation.
  • Diet has been suggested to play a very important role in the formation of an acne but no justified evidence has been laid to support this claim.
  • Infections caused by a bacteria species Propionibacterium acne is associated with acne but its pathophysiology is not well understood.


Acne normally occurs as a result of four main factors:

  • Excess production of sebum
  • Blockage of follicles with sebum and dead keratinocytes (keratin cells)
  • Colonization of follicles by Propionibacterium acnes (a normal human anaerobic bacteria)
  • The release of inflammatory mediators

Acne can be further divided into non-inflammatory or inflammatory acne based on the presentation of skin lesions.

Noninflammatory Acne: Presents as comedones (sebaceous plugs blocked within follicles). These are further classified into open or closed depending on the dilation of the follicle or closure of the follicle at the skin surface. Sebaceous plugs are easy to remove in open comedones but difficult to remove in closed comedones. Closed comedones often lead to inflammatory acne.

Inflammatory Acne: Presents as papules and pustules when P. acnes colonizes closed comedones. P. acnes causes the breakdown of sebum into fatty acids, irritating follicular epithelial cells and producing an inflammatory response by immune cells. This causes further destruction of the epithelium. Rupture of the inflamed follicle leads to the release of comedone content. The content produces a local inflammatory reaction producing papules. Progressive inflammation produces pustules.


Acne is most common in North American whites.Pomade accompanied acne is prevelant among African Americans. Particular ethnic groups with darker skin tone population, may show acne prevalence across natives. This likely due to the use of hair pomades. Ethnic groups with darker skin are most prone to acne keloidalis nuchae (keloid scars from acne formation).

In adolescence, acne vulgaris is more common in males than in females. However, in adulthood, it is more common in women than in men.


Many factors can predispose one to acne formation. The following are some of the factors:

  • Intrinsic Factors:

-Polycystic Ovary Syndrome

-Congenital adrenal hyperplasia

-Increased cortisol (Cushing’s Syndrome)
-Increased growth hormone (Acromegaly)

-Topical and systemic steroids

-Oral contraceptive pill (Higher androgen content)


  • Extrinsic Factors:


Coal and tar

Chlorinated phenols

DDT and weed killers


Acne mostly occurs on the face, neck, shoulders, back and upper chest. Acne is divided into three levels based on its severity in relation to symptoms. These are as follows:

  • Mild Acne:

Patients present with comedones and a few papules and pustules. These pustules present with yellow tops and are normally noninflamed. Open comedones (blackheads) present as small flesh-colored bumps with a dark center. Closed comedones (whiteheads) present similarly without a dark center, but a lighter(whitish) appearance.

  • Moderate acne:

Patients present with comedones (blackheads and whiteheads), inflammatory papules and pustules. There is an increase in the number of lesions as compared to mild acne.

  • Severe acne (Nodulocystic acne):

Patients present with large numbers of blackheads and whiteheads, pimples and pustules or cystic (deep) acne. Scarring is often evident. Nodules present have a diameter > 5mm. Five or more cysts can occur which are large, red, painful and filled with pus. These can merge under the skin into a larger abscess (large collection of pus).


Health practitioners usually look out for the following in order to diagnose acne. These are as follows:

-Presence of blackheads or whiteheads (comedones).
-Previous history of acne
Other factors that are assessed by the health practitioner include:
-Contributing risk factors (Hormones or drug-related)
-Psychosocial impact of acne (physical appearance in society)

*The basis of diagnosis is examination of the skin. When the diagnosis is confirmed, the severity of acne is graded into mild, moderate or severe based on the number and type of lesions.


Acne usually resolves spontaneously in the second decade of life (20 years), however in most female patients usually women, acne may occur in the third decade of life (30 years). Treatment options are limited due to childbirth concerns. Adults may randomly acquire mild acne lesions localized at one point. Acne that isn’t accompanied by inflammation often regress without scaring.

Non-inflammatory and mild inflammatory acne heal without scars. Moderate to severe inflammatory acne heals but often leaves scars. Acne often creates emotional stress in adolescents who find it as an excuse, to withdraw from personal adjustments in society.

Supportive counseling is required for patients indicated in severe cases.


Acne treatment is mostly based on the severity of the acne. The following are the treatment measures for acne:

  • Comedone: Topical tretinoin cream
  • Mild inflammatory acne: Topical retinoid, topical antibiotic, benzoyl perioxide
  • Moderate acne: Oral antibiotic with topical therapy for mild acne
  • Severe acne: Oral isotretinoin
  • Cystic acne: Intralesional triamcinolone (Injected corticosteroid)