Cheng-Wei Liu, BSc1; Jerry Tan, MD, FRCPC2

1Schulich School of Medicine & Dentistry, Western University, London, ON, Canada
2Faculty of Medicine, Western University, London, ON, Canada

Conflicts of Interest Disclosures:
Mr. Liu has nothing to disclose. Dr. Tan has served on an advisory board for Novartis, Cipher, Galderma, Valeant, and Roche; and has served as an investigator for Abbvie, BoehringerIngelheim, Pfizer, Novartis, Dermira, Galderma, and Xenon; and has received grants in compensation.

Introduction

Acne vulgaris (AV) is one of the most common skin diseases. Characterized by lesions resulting from inflammation of pilosebaceous units,1 predominant sites of involvement include the face, chest, and back – areas with the highest density of these units.1 Truncal acne refers to AV affecting the chest and/or back, a common presentation in acne patients.2 This article offers guidance in clinical differentiation of truncal acne from other acneiform diseases and provides management recommendations.

Background

  • Prevalence of truncal AV in those with facial acne is approximately 50%4, with 61% having lesions on the back and 45% on the chest.5
  • Current instruments measuring quality of life have only been validated for facial acne, however an instrument intended for both truncal and facial acne is now in development.6
  • Pathogenesis of acne has been described to be a complex process with four major pathogenic mechanisms: increased sebum production, colonization by Propionibacterium acnes, blockage of pilosebaceous ducts due to hyperkeratinisation, and inflammation.1

Clinical Presentation & Assessment

  • Acne lesions begin as microcomedones that become clinically apparent as open (blackheads) or closed (whiteheads) comedones.1
  • Erythematous papules and pustules develop when comedones become increasingly inflamed. If it becomes severe, deep pustules and nodules and/or cysts may develop.1
  • During the physical exam, individual assessment of the face, chest and back should be performed to evaluate severity and extent of disease.
  • Lesion types, size, distribution, and the presence of scars or dyspigmentation are important details to capture.7
  • Although several acne grading scales have been developed, few incorporate evaluations of truncal acne, and none are recommended for universal use.8
  • Practitioners should use a validated scale for facial and truncal acne for treatment selection and monitoring outcomes.8
  • The Comprehensive Acne Severity Scale (CASS) is one example of a grading scale validated for facial and truncal acne (Table 1) and can be applied separately to each of the face, chest and back.7
CategoryDescription
ClearNo lesions to barely noticeable ones. Very few scattered comedones and papules.
Almost clearHardly visible from 2.5 meters away. A few scattered comedones, and few small papules and very few pustules.
MildEasily recognizable, less than ½ affected area involved. Many comedones, papules, and pustules.
ModerateMore than ½ affected area involved. Numerous comedones, papules, and pustules.
SevereEntire area involved. Covered with comedones, numerous papules, pustules, nodules and cysts.
Very severeHighly inflammatory acne covering the affected area, with nodules and cysts present.
Table 1: Comprehensive Acne Severity Scale (CASS)

Differential Diagnoses

  • Several diseases affecting the trunk may mimic truncal acne.
    • Folliculitis is an inflammatory process caused by infection of hair follicles. The source of the infection may be fungal (Malassezia), bacterial (Staphylococcus, Pseudomonas) or viral (herpetic). Differentiating features include the absence of comedones and the presence of monomorphic lesions that may be pruritic.9,10
    • Pseudofolliculitis presents with inflammatory papulopustules due to ingrown hairs. This can be differentiated from truncal acne by the absence of comedones.11
    • Steatocystoma multiplex is a rare, autosomal-dominant disorder of the pilosebaceous unit that causes asymptomatic, yellow and/or skin-coloured cysts. Differentiating features include the monomorphic appearance and absence of inflammatory lesions.12

Management of Truncal Acne

Treatment Rationale & General Principles

  • Although truncal acne may not be the primary concern for facial acne patients, more than ¾ with incidental truncal acne desire treatment.13
  • Atrophic and/or hypertrophic scarring may result from truncal acne, therefore early diagnosis and effective management are important for prevention.2
  • Therapies should target the four processes that contribute to acne development: sebum production, bacterial colonization, ductal blockage due to hyperkeratinisation and inflammation.2
  • A combination approach targeting different mechanisms in pathogenesis should be considered.8
  • Selection of therapies should incorporate the practitioner’s clinical judgment, AV severity, prior history and patient preferences.
  • The following treatment recommendations are based on current acne guidelines and feature practical tips to facilitate management.

Topical Therapies

  • Topical therapies, available through prescription or over-the-counter, are effective agents that provide targeted therapy with minimal to no risk of systemic side effects.10
  • Evidence is lacking for topical management of truncal acne as studies are limited to facial acne. We infer that mechanisms and efficacy may also apply to truncal acne.
  1. Benzoyl peroxide (BPO) acts to decrease inflammation and hyperkeratinisation, and has antimicrobial properties.8 However, this may result in bleaching of clothing and bedding – of concern with truncal application.
  2. Retinoids (such as tretinoin, adapalene and tazarotene) decrease inflammation and follicular hyperkeratinisation, and are thus comedolytic and anticomedogenic.8
  3. Topical antibiotics, such as erythromycin and clindamycin, act to limit proliferation of P. acnes. However, they are not recommended as monotherapy due to the risk of bacterial resistance.8 In addition to joint use with BPO or topical tretinoin, fixed dose combinations of clindamycin with tretinoin and with BPO are available.
  4. Dapsone is anti-inflammatory and is effective in addressing inflammatory papules/pustules.8
  5. Azelaic acid is effective in reducing acne and postinflammatory hyperpigmentation.8

Practical Tips Based on Clinical Experience and Adapting Evidence in Facial Acne to Truncal Involvement

  1. Evaluate all areas of possible involvement and demonstrate topical application to the chest, shoulders, upper/mid/lower back as relevant.
  2. Consider topicals as first-line for truncal acne mild and moderate in severity.
  3. Effective agents include topical retinoids +/- BPO, topical retinoids + topical antibiotics; azelaic acid; dapsone.
  4. Apply a pea-sized amount of topical gel for surface area equivalent to two palms.
  5. Avoid spot treatment – apply broadly to zones of involvement to prevent new lesions.
  6. Note that benzoyl peroxide may lead to bleaching of clothing and bedding.

Systemic Therapies

Oral Antibiotics

  • Limit proliferation of P. acnes. Useful in moderate to severe acne, especially presentations that are resistant to topical therapies.8,14
  • Should not be used as monotherapy: a combination approach with BPO is recommended to enhance efficacy and reduce risk of bacterial resistance.8,14
  • Treatment should be kept as short as possible, ideally no more than 3-4 months, to reduce risk of bacterial resistance.8
  • Tetracyclines are considered first-line,8,14 however minocycline is not recommended when other options are available (e.g. tetracycline, doxycycline) as it has been associated with drug-induced hepatitis and lupus.14
  • Tetracyclines are contraindicated in those who are pregnant, allergic, or under the age of 8 years.8
  • Macrolides, such as erythromycin and azithromycin, are second-line agents used for patients with contraindications against tetracyclines.8 Erythromycin should be avoided due to increased risk of bacterial resistance.8
  • Use of other antibiotics is not recommended due to limited data on their efficacy and risk of bacterial resistance when they may be required for community acquired infections.8

Hormonal Therapies

  • Combined oral contraceptives (COCs) contain both estrogen and progestin, and act together to exert anti-androgenic effects through negative feedback mechanisms.8 Reduced circulating androgens has been linked to decreased sebum production.15
  • Most progestins are testosterone derivatives that are androgenic, especially those from earlier generations.8 Therefore, it is ideal to select COCs featuring newer progestins, such as norgestimate and drospirenone, that have minimal to no androgenic potential.8,14
  • COCs are effective in inflammatory acne in females, and may be particularly suitable for those with menstrual irregularities or who desire contraception.8
  • COCs are not recommended in patients who are pregnant, heavy smokers, aged greater than 35 years, have hypertension, diabetes, migraine headaches or history of DVT/PE.8
  • Spironolactone, despite its antiandrogenic effects and widespread use,16 has limited high quality evidence.8,14

Oral Isotretinoin

  • Isotretinoin is an oral retinoid that decreases sebum production, bacterial proliferation, hyperkeratinisation, and inflammation. Recommended for treating severe acne, and those resistant to other therapies.8,14
  • It is teratogenic,17 thus prescribers and female patients of child bearing potential must adhere to policies outlined by pregnancy prevention programs.8
  • Isotretinoin should be avoided in breastfeeding females as it may be transferred to infants through breast milk.8
  • Lab and clinical monitoring should include testing for liver function, serum cholesterol, TGs, and psychiatric disturbances.8
  • Prescription should be limited to physicians who are trained and experienced in its use.14

Practical Tips

  1. When prescribing oral antibiotics, limit duration and use with topical BPO to reduce risk of antibiotic resistance.
  2. Systemic agents confer greater risk of side effects than topicals alone.
  3. Truncal acne responds more slowly than facial acne.

Conclusions

  • Truncal acne is common in patients presenting with acne, and may be underdiagnosed and undertreated.2
  • Other skin disorders may result in lesions that resemble truncal acne, thus careful examination for differentiating features can assist in accurate diagnosis.
  • Treatments for truncal AV are derived from recommendations for facial AV.2 Evaluate for response at 2-3 months and consider escalation if inadequate improvement.
    • For mild and moderate severity – consider topical retinoids (with or without topical antibiotics or BPO); azelaic acid; dapsone.
    • For moderate and moderate/severe presentations, consider a combination of topical therapies with systemic antibiotics or COCs in females.
    • For severe truncal acne – oral isotretinoin is the treatment of choice.
      • Oral antibiotics and topicals (retinoids + BPO or topical antibiotics) and ethinyl estradiol/cyproterone acetate are alternatives if patients are intolerant, unable or unwilling to consider oral isotretinoin.

References

  1. Degitz K, Ochsendorf F. J Dtsch Dermatol Ges. 2017 Jul;15(7):709-722.
  2. Bikowski J. J Clin Aesthet Dermatol. 2010 Nov;3(11):26-9.
  3. White GM. J Am Acad Dermatol. 1998 Aug;39(2 Pt 3): S34-7.
  4. Del Rosso JQ. Cutis. 2006 May;77(5):285-9.
  5. Tan JK, et al. J Drugs Dermatol. Jun;7(6):551-6.
  6. McLellan C, et al. Development of a Comprehensive Quality of Life Measure for Facial and Torso Acne. [Under Review].
  7. Tan JK, et al. J Cutan Med Surg. 2007 Nov-Dec;11(6):211-6.
  8. Zaenglein AL, et al. J Am Acad Dermatol. 2016 May;74(5):945-73.e33.
  9. Rubenstein RM, Malerich SA. J Clin Aesthet Dermatol. 2014 Mar;7(3):37-41.
  10. Gjede J, Graber E. Infectious diseases mimicking acne vulgaris: Bacterial folliculitis In: Zeichner, J, ed. Acneiform Eruptions in Dermatology: A Differential Diagnosis. 1st ed. New York, NY: Springer; 2014:43-47.
  11. Coley MK, et al. Pseudofolliculitis barbae and acne keloidalis nuchae. In: Alexis AF, Barbosa VH, eds. Skin of Color. 1st ed. New York, NY: Springer; 2013:123-137.
  12. Varshney M, et al. BMJ Case Red. 2011 Sep;2011. pii: bcr0420114165. doi: 10.1136/bcr.04.2011.4165.
  13. Del Rosso JQ, et al. Prevalence of truncal acne vulgaris: a population study based on private practice experience. Poster presented at: 65th Annual Meeting of the AA; Feb 2-6, 2007;Washington, DC.
  14. Asai Y, et al. CMAJ. 2016 Feb;188(2):118-26.
  15. O’Connell K, Westhoff C. Cutis. 2008 Jan;81(S1):8-12.
  16. Brown J, et al. Cochrane Database Syst Rev. 2009 Apr 15;(2):CD000194.
  17. Lammer EJ, et al. N Engl J Med. 1985 Oct;313(14):837-41.
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