USE OF DERMAL FILLERS IN ATROPHIC ACNE SCARRING

Acne vulgaris is a chronic skin disease characterised by the occurrence of skin lesions such as open and closed comedones, pustules, papules, and cysts.1

More than 80% of adolescents, 50–60% of women aged 20–25 years, and 12% of women over 25 suffer from acne. Factors that cause the disease include abnormal keratinisation of the pilosebaceous canal, increased sebum production, bacterial colonisation, and inflammatory and hormonal disorders of the skin.2

Acne scarring is a relatively common outcome of acute acne, with an estimate of 80% of acne scars being atrophic, with ice pick scars at 60%, boxcar scars at 25%, and rolled scars at 15%.3 Acne is characterised by follicular hyperkeratinisation and sebum overproduction, mediated by androgens in the pilosebaceous unit. The bacterium P. acnes proliferates in this situation, potentially triggering an inflammatory response which can lead to scarring. There is a higher risk of scarring with a prolonged inflammatory response and unbalanced ratio of matrix metalloproteinases (MMPs) to tissue inhibitors of MMPs (TIMPs) during the extracellular matrix remodeling (ECM) process.4

Acne scarring is challenging to treat, therefore prevention of scars by early aggressive treatment to reduce inflammation is key and sadly often ignored by patients and physicians. There is evidence that the use of retinoids is helpful in reducing the inflammation. Oral retinoids are more effective than antibiotics in the prevention of acne scarring5 and topical retinoids may also play a role in prevention.6

▼ TYPES OF ACNE SCAR

Ice pick scars are deep, narrow, and can reach the border of the dermis with the subcutaneous tissue. They have sharp edges, a width of not more than 2mm, and a V-shaped cross-section with a narrowing deep into the skin. Boxcar scars are oval or round, but quite wide and flat, and resemble the letter U or a square. Their edges are well marked and have a demarcated edge. They are usually 0.1–0.5mm deep and 1.5–4mm wide. They can combine to form clusters. Boxcar scars have the cross-section of the letter M, while rolling scars are the largest of all types and can reach a diameter of 5mm.7

TREATMENT OF ACNE SCARS

The treatment of acne scars is dependent on the type of scar, the extent and severity, together with the downtime and preferences of patients and clinicians. There is no consensus for the best treatment regime, but most clinicians agree that treatment results are best with a combination of therapies for a longer period. Lasers, both ablative and non-ablative, radiofrequency (RF) and standard microneedling, the chemical reconstruction of skin scars using trichloroacetic acid (TCA Cross), peels, subcision, punch excision and platelet-rich plasma (PRP) all have evidence of success in treating scars. This article focusses on the use of injectable substances for the improvement of acne scars.

Injectable substances can be divided into hyaluronic acids (HA) and collagen stimulators such as polylactic acid (PLLA), calcium hydroxyapatite (CaH) and polymethyl methacrylate (PMMA).

These treatments are readily available and easy to administer, and they appear to have a good side-effect profile.

HA DERMAL FILLERS

It is quite difficult to conclude what type of HA filler is most suitable and which technique is best due the terminology and design of various studies. Mehrabi, Joseph et al. (2023)8 compared a traditional cross-linked HA filler with a low molecular weight, non-cross-linked HA and found differences in initial results, but good longer term results treating acne scars, although they did not state what type of scar they treated.

Another study using a cross-linked HA injecting in the dermis until it raised a bleb, which was massaged flat, showed a good improvement in rolling acne scars. Another study using a modified tower technique and high lift HA achieved high patient satisfaction.9 A review by Abdel Hay R., Shalaby K., Zaher H., et al. in 201610 noted no difference in adverse events following dermal filler injection for acne scars compared with placebo.

The goal of treatment is to lift the scar and improve skin quality both generally and within the scars.

In conclusion, the best types of scars for dermal filler treatment are rolled scars, followed by boxcar scars. Volumising dermal fillers with greater cross-linking are more likely to provide volume, but are better injected in the deep dermis or deeper, as superficial injection may create a lump which is more difficult to flatten, and a modified tower technique may be useful. Less cross-linked fillers can be injected superficially but provide less lift. The problem with HA fillers is that they are not long lasting and create less collagen11 compared with other products such as PLLA and CaH, requiring more frequent multiple injections over time.

I conclude that HA fillers are best reserved for shallow rolled or boxcar scars.

CAH FILLERS

Longer lasting than HA filler, CaH fillers have shown good results in studies of acne scars.12 Another study using diluted CaH in cross hatched lines with micro-focussed high intensity focussed ultrasound (HIFU) showed good results with no adverse issues.13 Another found CaH just as good as monotherapy.14

Other studies15 found a combination of subcision and CaH helpful in rolled and boxcar scars, but not icepick scars.

PLLA FILLERS

PLLA has been shown to have clinical benefits for up to two years.16 Beer (2007)17 found that shallow broad scars respond well to PLLA but required seven sessions. Sapra S., Stewart JA., Mraud K., Schupp R. (2015)18 showed excellent results (44% excellent patient satisfaction) from three sessions of PLLA in rolled acne scars with only one nodule formed.

PLLA is safe if injected in the deep dermis or deeper, and is effective in long-term improvement of rolled and shallower boxcar scars. It is not effective in ice pick scars. It is superior to HA due to its longevity.

PMMA FILLER

Joseph et al. (2019)19 found improved results in 90% after seven months with PMMA for full face acne treatment with minimal side effects. Solomon P., et al. (2021)20 found it to be a safe product over multiple applications. Another study by the US Food and Drug Administration in 201421 found good efficacy and safety in the treatment of acne scars.

NEW COMBINATION FILLERS

HA/CaH and HA/PLLA gels have recently become available, and these theoretically could be useful in treating acne scarring.

CONCLUSION

Atrophic acne scarring is challenging to treat and requires a combination of treatments to obtain the best results. Given the current research, rolling scars respond best to injectable treatments, followed by shallow boxcar scars. Longer acting fillers such as CaH, poly-d-lactic acid and PMMA are best suited to treating these scars. Injection methods vary, but need to be at least deep dermal, and can be global or more localised. With correct techniques, these products appear to have minimal side effects and reasonable efficacy. However, current research is as yet inadequate to determine best practice.

REFERENCES

1. Leccia MT, Auffret N, Poli F, Claudel JP, Corvec S, Dreno B. Topical acne treatments in Europe and the issue of antimicrobial resistance. J Eur Acad Dermatol Venereol. 2015 Aug;29(8):1485-92.

2. Contassot E., French L.E. New insights into acne pathogenesis: propionibacterium acnes activates the inflammasome. J. Investig. Dermatol. 2014;134:310–313.

3. Jacob CI, Dover JS, Kaminer MS. Acne scarring: a classification system and review of treatment options. J Am Acad Dermatol. 2001;45(1):109– 117.

4. Fabbrocini G, Annunziata MC, D’Arco V, et al. Acne scars: pathogenesis, classification and treatment. Dermatol Res Pract. 2010;2010:1–13.

5. Agrawal DA, Khunger N. A morphological study of acne scarring and its relationship between severity and treatment of active acne. J Cutan Aesthet Surg. 2020 Jul-Sep;13(3):210-216.

6. Tan J, Tanghetti E, Baldwin H, Stein Gold L, Lain E. The role of topical retinoids in prevention and treatment of atrophic acne scarring: Understanding the importance of early effective treatment, Journal of Drugs in Dermatology : JDD. 2019 Mar;18(3):255-26.

7. Connolly, D.; Vu, H.L.; Mariwalla, K.; Saedi, N. Acne scarring-pathogenesis, evaluation, and treatment options. J. Clin. Aesthet. Dermatol. 2017, 10, 12–23.

8. Mehrabi, Joseph MD; Shehadeh, Waseem MD; Gallo, Elisa S. MD; Artzi, Ofir MD; Horovitz, Tamir MD. Comparison of two HA-based fillers for the treatment of acne scars: structural lifting versus biostimulatory effect. Dermatologic Surgery 49(6):p 581-586, June 2023.

9. Goodman, G. J., & Van Den Broek, A. (2016). The modified tower vertical filler technique for the treatment of post-acne scarring. Australasian Journal of Dermatology, 57(1), 19-23.

10. Abdel Hay R, Shalaby K, Zaher H, et al. Interventions for acne scars. The Cochrane Database of Systematic Reviews. 2016

11. Mercer SE Kleinerman R Goldenberg GE Manuel PO Histopathologic identification of dermal filler agents J Drugs Dermatol 2010.

12. Goldberg DJ, Amin S, Hussain M (2006) Acne scar correction using calcium hydroxylapatite in a carrier-based gel. J Cosmet Laser Ther 8:134–136.

13. Gabriela Casabona (2018) Combined use of micro focused ultrasound and a calcium hydroxylapatite dermal filler for treating atrophic acne scars: A pilot study, Journal of Cosmetic and Laser Therapy, 20:5, 301-306.

14. Antonino, A. and Francesco, A. (2020). Prospective and randomised comparative study of calcium hydroxylapatite vs calcium hydroxylapatite plus HIFU in treatment of moderate-tosevere acne scars. Journal of Cosmetic Dermatology, 20(1), 53-61.

15. Treacy P. Treatment of acne scars with Radiesse, London Aesthetic Medicine 200.

16. Hanke CW, Redbord KP (2007) Safety and efficacy of poly-l-lactic acid in HIV lipoatrophy and lipoatrophy of aging. J Drugs Dermatol 6:123–128.

17. Beer K (2007) A single-center, open-label study on the use of injectable poly-l-lactic acid for the treatment of moderate to severe scarring from acne or varicella. Dermatol Surg 33(Suppl 2):S159– S167.

18. Sapra S, Stewart JA, Mraud K, Schupp R. A Canadian study of the use of poly-L-lactic acid dermal implant for the treatment of hill and valley acne scarring. Dermatol Surg. 2015 May;41(5):587-94. 19. Joseph, John H. MD; Shamban, Ava MD; Eaton, Laura RN, BSN; Lehman, Alayne RN, BSN, MS; Cohen, Steven MD; Spencer, James MD, MS; Bruce, Suzanne MD; Grimes, Pearl MD;

Tedaldi, Ruth MD; Callender, Valerie MD; Werschler, Phillip MD. Polymethylmethacrylate collagen gel– injectable dermal filler for full face atrophic acne scar correction. Dermatologic Surgery 45(12):p 1558-1566, December 2019.

20. Solomon P, Ng CL, Kerzner J, Rival R. Facial soft tissue augmentation with bellafill: A review of four years of clinical experience in 212 patients. Plastic Surgery. 2021;29(2):98-102 21. US Food and Drug Administration. FDA; 2014. Available from: accessdata.fda.gov/cdrh_docs/pdf2/ P020012S009b.pdf.