How to deal with Truncal Acne?

Acne, also known as acne vulgaris, is one of the commonest reason for a patient to visit a dermatologist. Truncal acne is when acne develops in the back or the chest. Most of the data and scientific studies available are concentrated facial acne, while less emphasis has been placed on truncal acne.

It has been shown that at least 50% of patients with facial acne also had truncal acne and 3% had complaints of truncal acne alone. So yes, it is possible for someone to suffer from truncal acne without ever having facial acne.

Most patients do not seek treatment specifically for their truncal acne. It is only when they’re asked for directly by their doctors or when undergoing a full clinical evaluation for their facial acne that they are raise their concern about their truncal acne as well.

How does acne develops?

It takes more to develop acne than just an oily skin.

Acne is a mutifactorial disease, caused by a complex interplay between genetics, hormones, micro organisms and inflammation.

The four main pathological process are: i) abnormal follicular keratinisation (anomaly in the process of how the cells of the skin differentiate into a layers of dead skin cells which are eventually shed off), (ii) increase sebum production (oily secretion produced by glands in the skin), (iii) Colonization by Propionibaceterium acnes (bacteria normally found on the surface of the skin but increase in number in acne vulgaris patients) and lastly, (iv) Inflammation (body’s natural response to the above three factors).

fig. How acne develops (simplified version).
Red indicates the site of action of various acne medications
fig. Acne formation (CC-BY)

Challenges for treatment of truncal acne

As I mentioned earlier, limited studies are available on management of truncal acne. From the studies that are available, the treatment modality is based on the severity of the acne.

Treating truncal acne can be challenging due to the large surface area of involvement. The topical medication such as face washes or creams may not be feasible for use on the back.

For this reason, different formulations such as foams, lotions or body washes are required for such large area. The problem with this type of formulation is that they are the least potent form of drug delivery system which deliver the least amount of active ingredient (benzoyl peroxide or salicylic acid etc).

fig. Potency of topical formulations
Icons credits CC-BY: 1, 2, 3, 4, 5, 6

Why see a dermatologist for truncal acne?

Treatment of truncal acne follows the same principle as for facial acne. The treatment will vary among individuals and depending on the severity of the acne. Unfortunately, there is still no definite cure for this condition. One ray of hope is that truncal acne has lesser chances of scarring as compared to facial acne. The treatment options available are limited and for optimal results, consistency and long term maintenance is necessary for better control of the breakout and minimizing the chances of scarring.

A thorough evaluation by a dermatologist is necessary, for assessment of the severity, other relevant medical or drug history which may be the cause of the acne or to rule out any medical contraindication to a specific acne treatment.

There are many other conditions that can resemble truncal acne. Some of these conditions are acneiform eruption (acne caused by certain medications such as anabolic steroids, anti fungal drugs, or exposure to insectisides, mechanical trauma as seen in areas of contact with bra straps), gram negative folliculitis, and P.follicultis.

All red bumps on the back or chest is not acne.

Treatment options available for truncal acne

For mild truncal acne, a topical benzoyl peroxide wash available as 4%, 8% and 10% creamy wash once a day for at least 12 weeks. Washes are applied to the entire back and chest at the time of shower for a contact time of 20 seconds followed by rinsing with normal water. The method of application as stated in the article “Benzoyl Peroxide Cleansers for the Treatment of Acne Vulgaris: Status Report on Available Data”

Mild truncal acne

“20-10 approach” of gentle massage application to lightly moistened skin (a 20-second contact time) and gentle rinsing over an approximate 10-second period.

A longer contact time of more than 20 seconds may cause some irritation. Another drawback of benzoyl peroxide is that it can cause bleaching of the clothes that comes it contact with.

Benzoyl peroxide 4% (brevoxyl creamy wash) available in India

For moderate acne, addition of a topical antibiotic such as clindamycin available as foam cleansers can be beneficial. A systemic antibiotic may be required if response to the above topical medication is poor. Recently, topical dapsone (antibiotic) has also been shown to help improve truncal acne.

For severe acne, or truncal acne that fails to respond to the above mentioned treatment, systemic management with retinoid (isotretinoin) or hormonal therapy such as oral contraceptive pills are indicated. These treatment will require a thorough clinical assessment and certain baseline blood investigations prior to the initiation of therapy. Regular follow up will be necessary with such treatment.

Which soap to choose?

A recent study has shown that the pH of the skin at the back is higher compared to the pH of the skin on the face and chest. This alkaline pH at he back favors the growth and multiplication of Propionebacterium acnes in these areas which then contribute to the etiology of truncal acne. Avoiding soaps that can further increase this pH will be beneficial. Opt for a syndet (i.e. synthetic detergent) bar or body washes with neutral pH for example dove soaps are syndet bars which does not alter the skin’s pH.

It’s important to remember that similar to facial acne, truncal acne can be controlled with the occasional flare but with a consistent regimen the number of breakout can be reduced and scarring can be prevented. One gentle reminder which all of us are aware of yet fail to comply is to avoid picking on the acne.