Acne

Acne is a very common skin condition where hair follicles under the skin become clogged. Sebum—oil that helps keep skin from drying out—and dead skin cells plug these pores, leading to outbreaks of lesions, commonly called pimples or zits. The medical term for acne is acne vulgaris. Most often, these outbreaks occur on the face but can also appear on the back, chest, and shoulders. Primarily, it is an inflammatory disorder of the pilosebaceous unit. (1)

Figure 1: The pilosebaceous unit (2)

In healthy skin, the sebaceous glands make sebum which empties onto the skin surface through the pore, which is an opening in the follicle. Keratinocytes, a type of skin cell, line the follicle.  Normally as the body sheds skin cells, the keratinocytes rise to the surface of the skin. When someone has acne, the hair, sebum, and keratinocytes stick together inside the pore. This prevents the keratinocytes from shedding and keeps the sebum from reaching the surface of the skin. The mixture of oil and cells allows bacteria that normally live on the skin to grow in the plugged follicles and cause inflammation—swelling, redness, heat, and pain. When the wall of the plugged follicle breaks down, it spills the bacteria, skin cells, and sebum into nearby skin, creating lesions or pimples. (1)

For most people, acne tends to go away by the time they reach their thirties, but some people in their forties and fifties continue to have this skin problem.

Due to the varied nature of this condition, there are numerous types of acne: (3)

• Acne rosacea 

• Acne fulminans/conglobata

• Fungal acne

• Cystic acne

Figure 2:  Moderate fungal acne (4)

What causes acne?

Acne can be caused by a single factor or due to a combination of many. Some of these include:

• Genetic history

• Endogenous and exogenous androgenic hormones

• Poor hygiene

• Psychological factors

On a background of acne, flares can be provoked by: (5)

• Polycystic ovarian disease

• Drugs e.g. steroids, hormones, anticonvulsants

• Application of occlusive cosmetics

• High environmental humidity

Figure 3: Steroid-induced acne vulgaris (6)

Clinical features of acne

Due to the variable nature of skin, acne has a diverse variety of clinical features. It can present with: (7)

• Comedones
  

• This is an oil and dead skin cell clogged hair follicle. These can develop into whiteheads and blackheads. Skin products labelled as “noncomedogenic” are less likely to clog pores and contribute to acne.

• Blackheads
  

• These are comedones which are open at the surface of the skin. They are filled with excess oil and dead skin cells. Its not dirt which causes the comedone to turn black. The black hue results from the irregular reflection of light coming from clogged hair follicles.

• Whiteheads
  

• Comedones which stay closed at the surface of the skin are called whiteheads. This happens when oil and skin cells prevent a clogged hair follicle from opening. Many of the same over-the-counter medicines which treat blackheads are also effective against whiteheads.

• Papules 
  

• These are comedones which become inflamed, forming small red or pink bumps on skin. They can be sensitive to touch.

• Pustules
  

• Pustules are another kind of inflamed skin pimple. They resemble a whitehead with a red ring around the bump. The bump is typically filled with white or yellow pus. Avoid picking or squeezing pustules. Picking can cause scars or dark spot development.

• Nodules

• Nodules are large, inflamed bumps which feel firm to the touch. They develop deep within the skin and are often painful. These should be treated by a dermatologist since they can scar. Usually prescription drugs are required to be effective.

Figure 4: Cystic Nodule (7)

• Cysts

• Cysts are large, pus-filled lesions that look similar to boils. Like nodules, cysts can be painful and should be treated by a dermatologist since they also can scar. Cysts usually form a picture of severe acne.

Acne Rosacea

Acne Rosacea is a long-term inflammatory skin condition that causes reddened skin and a rash, usually on the nose and cheeks. It may also cause eye problems. The symptoms typically come and go, with many people reporting certain factors, such as spending time in the sun or experiencing emotional stress, bring them on. (8)

Figure 5: Acne Rosacea on the face (9)

Whilst this has no cure, treatment can keep this under control. The choice of treatment will depend on the symptoms, and usually includes a combination of self help measures and medications. (8)

Acne Fulminans

Acne fulminans is a rare and very severe form of acne conglobate associated with systemic symptoms. It nearly always affects adolescent males. It usually affects areas such as the forehead, shoulders, chest and back. (10)

Figure 6: Acne fulminans affecting the back (11)

This condition is associated with increased androgens (male sex hormones), autoimmune complex disease and genetic predisposition. It may be related to an explosive hypersensitivity reaction to surface bacteria (Cutibacteria acnes). (10)

It is commonly precipitated by: (10)

• Testosterone and anabolic steroids (legally prescribed or illegally taken to enhance muscle growth)

• Oral isotretinoin

Those affected require an urgent referral to a dermatologist. 

Investigations

Acne is a clinical diagnosis and investigations are rarely required.

Acne Management (5)

Mild acne

• Topical agents such as benzoyle peroxide (chemical exfoliant) or adapalene (mild retinoid) gel.

• pH balanced washes with salicylic acid

Moderate acne

This treatment commonly comprises of mild acne treatment with an antibiotic:

• a tetracycline such as doxycycline 50-200 mg daily for 6 months

• Erythromycin or trimethoprim if doxycycline intolerant

• Isotretinoin is often used if acne is persistent or treatment-resistant

Severe acne

• Higher dose of antibiotics

• Oral isotretinoin in suitable patients

This type of acne always requires a referral to a dermatologist. It should be urgent to reduce the occurrence of complications.

Complications

Complications of chronic acne include:

• Atrophic scars e.g. ice pick scars or hypertrophic keloid scars 

• Skin hyperpigmentation – more common in darker skin tones

Figure 7: Post Inflammatory hyperpigmentation (12)

We hope you enjoyed this month’s post all about acne! 

Remember this is a hugely diverse condition with many variants and different presentations.

Keep your eyes peeled for practice questions on acne which will be released soon ;)

References

1. Acne [Internet]. 2024. Available from: https://www.niams.nih.gov/health-topics/acne

2. Sebaceous gland [Internet]. 2024 Available from: https://en.wikipedia.org/wiki/Sebaceous_gland

3. Acne [Internet]. 2024. Available from: https://my.clevelandclinic.org/health/diseases/12233-acne

4. Fungal Acne: An In-Depth Exploration [Internet]. 2024. Available from: https://averraglow.com/blogs/news/fungal-acne

5. Acne [internet]. 2024. Available from: https://dermnetnz.org/topics/acne

6. Steroid Acne [Intrnet]. 2024. Available from: https://dermnetnz.org/topics/steroid-acne

7. Slideshow: Acne Visual Dictionary [Internet]. 2024. Available from: https://www.webmd.com/skin-problems-and-treatments/acne/ss/slideshow-acne-dictionary

8. Rosacea [Internet]. 2024. Available from: https://www.niams.nih.gov/health-topics/rosacea 

9. New study examines differences between rosacea and acne [Internet]. 2024. Available from: https://www.rosacea.org/blog/2017/may/new-study-examines-differences-between-rosacea-and-acne

10. Effective treatments of atrophic acne scars [Internet]. 2024. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4445894/

11. Acne Fulminans [Internet]. 2024. Available from: https://dermnetnz.org/topics/acne-fulminans

12. Aumello [Internet]. 2024. Available from: https://aumello.com/blogs/news/how-to-prevent-and-get-rid-of-dark-spots-hyperpigmentation-and-acne-scars