Post-inflammatory hyperpigmentation — SAQ

Stem

A 24-year-old woman with deeply pigmented skin presents with flat brown marks on both cheeks. Each mark appeared after an acne papule settled. New acne lesions are still developing, and an online “lightening” cream stings when applied. The marks are more noticeable after sun exposure. Wood's lamp examination produces mild contrast enhancement in some, but not all, lesions. There is no oral-mucosal or palmar-crease pigmentation and she is otherwise well. [4][5]

Questions and model answers

a) State the most likely diagnosis and give two findings that support it. (3 marks)

1. Acne-associated post-inflammatory hyperpigmentation (PIH). (1 mark)
2. The lesions are flat brown macules that appeared after inflammatory acne. (1 mark)
3. They occupy the same sites as the healed acne lesions. Skin tone and Wood's lamp findings may modify assessment but neither is diagnostic. (1 mark) [4][5]

b) Give four components of a focused assessment. (4 marks)

1. Confirm chronology and other possible triggers, including picking, procedures, medicines and all applied products. (1 mark)
2. Examine for active acne or irritant dermatitis, and document morphology, distribution and colour. (1 mark)
3. Estimate pigment depth cautiously: brown suggests an epidermal component; Wood's lamp may support but cannot confirm depth, especially in deeply pigmented skin. (1 mark)
4. Look for discordant clues such as no precursor, symmetry typical of melasma, prolonged lightener use suggesting ochronosis, generalised/mucosal pigment or a solitary changing lesion. Typical localised PIH needs no routine blood tests; investigate or biopsy only for the suspected alternative. (1 mark) [5][7][9]

c) Outline a six-point management plan. (6 marks)

1. Treat active acne with a tolerable evidence-based acne regimen to prevent new PIH. (1 mark)
2. Stop the stinging unlabelled lightener and treat any irritant dermatitis; counsel against picking without blaming the patient. (1 mark)
3. Recommend consistent broad-spectrum sunscreen, shade and clothing. (1 mark)
4. Offer tinted iron-oxide sunscreen if acceptable because it can add visible-light protection; explain that this supports prevention and does not guarantee clearance. (1 mark)
5. Once irritation is controlled, discuss one compatible topical option such as clinician-supervised hydroquinone, a topical retinoid that also treats acne, or azelaic acid. Start gently and review tolerability rather than stacking irritants. (1 mark)
6. Refer for dermatology review if the diagnosis is uncertain, products suggest ochronosis, distress remains substantial, or a peel/device is being considered; procedures may improve PIH but can also worsen it. (1 mark) [1][2][4][6][8]

d) Give two counselling or safety statements. (2 marks)

1. Improvement is usually gradual over months and dermal pigment can persist for years; complete clearance is not assured because trials more often report partial than complete response. (1 mark)
2. Return earlier for a changing solitary lesion, generalised or mucosal pigmentation with systemic symptoms, or blue-black change after prolonged lightener use. Reassess diagnosis, continuing inflammation, adherence and irritation if progress is poor rather than promising automatic laser escalation. (1 mark) [1][2][7][10]

References

1. [1]Mar K, Khalid B, Maazi M, et al. Treatment of Post-Inflammatory Hyperpigmentation in Skin of Colour: A Systematic Review. J Cutan Med Surg, 2024.PMID 39075672
2. [2]Kashetsky N, Feschuk A, Pratt ME. Post-inflammatory hyperpigmentation: A systematic review of treatment outcomes. J Eur Acad Dermatol Venereol, 2024.PMID 37843491
3. [3]Maghfour J, Olayinka J, Hamzavi IH, et al. A Focused review on the pathophysiology of post-inflammatory hyperpigmentation. Pigment Cell Melanoma Res, 2022.PMID 35306737
4. [4]Elbuluk N, Grimes P, Chien A, et al. The Pathogenesis and Management of Acne-Induced Post-inflammatory Hyperpigmentation. Am J Clin Dermatol, 2021.PMID 34468934
5. [5]Silpa-Archa N, Kohli I, Chaowattanapanit S, et al. Postinflammatory hyperpigmentation: A comprehensive overview: Epidemiology, pathogenesis, clinical presentation, and noninvasive assessment technique. J Am Acad Dermatol, 2017.PMID 28917451
6. [6]Chaowattanapanit S, Silpa-Archa N, Kohli I, et al. Postinflammatory hyperpigmentation: A comprehensive overview: Treatment options and prevention. J Am Acad Dermatol, 2017.PMID 28917452
7. [7]Wang RF, Ko D, Friedman BJ, et al. Disorders of hyperpigmentation. Part I. Pathogenesis and clinical features of common pigmentary disorders. J Am Acad Dermatol, 2023.PMID 35151757
8. [8]Lyons AB, Trullas C, Kohli I, et al. Photoprotection beyond ultraviolet radiation: A review of tinted sunscreens. J Am Acad Dermatol, 2021.PMID 32335182
9. [9]Narayan R V, Thakur V, Bishnoi A, et al. Acquired dermal macular hyperpigmentation: a unified spectrum of dermal pigmentary dermatoses. Clin Exp Dermatol, 2026.PMID 41700520
10. [10]Bornstein SR, Allolio B, Arlt W, et al. Diagnosis and Treatment of Primary Adrenal Insufficiency: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab, 2016.PMID 26760044