Abstract

Postinflammatory hyperpigmentation (PIH) – an acquired hypermelanosis occurring after cutaneous inflammation or injury, can affect all skin types, however, it is more frequent in dark-skinned patients. PIH can occur in both genders and may precipitate from numerous factors or triggers that induce an inflammatory reaction, such as – inflammatory reaction, induced by cutaneous diseases including acne vulgaris, atopic dermatitis, psoriasis, impetigo, lichen planus, pityriasis rosea, irritant and allergic contact, photocontact-dermatitis, insect bites, burns or cosmetic procedures. PIH results from the melanocytes response to the cutaneous insult of inflammation—causing increased synthesis and/or redistribution of melanin. Additionally, epidermal inflammation also causes damage to the basal layer resulting in leakage of melanins from basal keratinocytes and accumulation of melanophages in the dermis—thereby exacerbating dermal hyperpigmentation.

Introduction 

Postinflammatory hyperpigmentation (PIH) – an acquired hypermelanosis or pigmentary skin disorder, occurs as a result of an inflammatory reaction of the skin. These can be triggered by cutaneous diseases, for example – acne vulgaris, atopic dermatitis, psoriasis, impetigo, lichen planus, pityriasis rosea, irritant and allergic contact and photocontact-dermatitis, or due to medication-induced hypersensitivity reactions, cutaneous injury from irritants, UV exposure, burns, cosmetic procedures or insect bites.

The severity and frequency of PIH are higher in individuals with skin of color of both genders. Among Indians, acne is a major cause of pigmented postinflammatory marks, which is more common in adolescents and adults as compared to the older age-groups. PIH may be persistent and tend to impact the quality of life of individuals. 

Prolonged inflammation increases the likelihood of inducing PIH. Cutaneous inflammation stimulates the epidermal melanocytes leading to an increased synthesis and/or redistribution of melanin. In addition, inflammation also causes damage to the basal layer resulting in the leakage of melanins from basal keratinocytes, followed by the accumulation of melanophages in the dermis—thereby exacerbating dermal hyperpigmentation.¹

Etiologies for facial PIH include infections such as dermatophytoses or viral exanthems, allergic reactions from insect bites or contact dermatitis, papulosquamous diseases such as psoriasis or lichen planus, medication-induced hypersensitivity reactions, and cutaneous injury from irritants, burns or cosmetic procedures. Systemic conditions causing facial noninflammatory hyperpigmentation include Peutz–Jeghers syndrome, Addison′s diseases, malignant melanoma, hemochromatosis, thyrotoxicosis, drug eruptions and ochronosis. Perioral dermatitis is characterized by erythematous red papules or papulopustules involving skin around the lips, with a characteristic clear zone adjacent to the vermilion border of the lips. Often, perioral dermatitis appears to be related to the application of one or more cosmetic preparations, topical corticosteroids, tartar control toothpaste or frequent chewing of bubble gum. Perioral dermatitis is a form of contact dermatitis that occurs due to repeated wetting and drying of the skin associated with persistent lip licking or thumb sucking, especially during the winter months.²

Case Report

A 13-year-old boy complained of an asymptomatic blackish demarcation around the lips.

The perioral encirclement was first observed about two days prior. He reported of experiencing dry lips along with rash and scaling around the lips, during winter. He used to wet his lips with saliva to get rid of dryness. Although the skin dryness disappeared within a week, blackish pigmentation started appearing on the same area soon. There was no history of previous hyperpigmentation, systemic/dermatological illness, recent medication, topical applications of emollients or change in toothpaste.

Clinical examination showed an isolated blackish discoloration of 0.5cm thick macular demarcation surrounding his lips with a characteristic clear zone around the lips. The oral mucosa and other areas of the skin were found unaffected.

The diagnosis was postinflammatory perioral hyperpigmentation that had occurred due to perioral contact dermatitis. The boy was advised to avoid lip-licking. He was prescribed a skin brightening agent containing niacinamide and arbutin, to be applied during evenings and a sunscreen to be used in the mornings. 

After two weeks of regular use of these emollients, the pigmented demarcation started fading. Continued usage for three weeks resulted in remarkable disappearance of the pigmentation. The patient and his parents were satisfied with this therapy. 

Discussion

Individuals with darker skin phenotypes have higher melanin content, higher eumelanin to pheomelanin ratio and better distribution of melanin for the protection against ultraviolet (UV) radiation. In addition, they have non-aggregated and larger melanosomes with greater total melanin content. Melanin protects against harmful effects of UV radiation, but predisposes to hyperpigmentation. 

Diagnosis of PIH involves a detailed history taking; complicated cases can be aided with a biopsy for histopathological evaluation. Disorders such as melasma, morphoea, atrophoderma, fixed drug eruptions and other rarer triggers must be considered. Management entails identification of the underlying inflammatory factor and eradication of the cause. Skin-lightening agents and sunscreens can be prescribed. In severe cases, chemical peeling agents and lasers may aid in achieving faster results; however, these can cause worsening of the lesion and thus, treatment strategies should be individualized based on the patient’s characteristics.²

Conclusion

This article reports an asymptomatic blackish skin pigmentation surrounding the lips in a 13-year-old boy, which had appeared after a recent episode of dryness of the lips during winter months. The teenager reported of frequently wetting his lips with saliva as a habit to get rid of dryness. Although his skin dryness disappeared within a week, dark discoloration started appearing on the skin around his lips. Clinical examination showed an isolated blackish discoloration, characterized as macular demarcation surrounding the lips with a central clear zone. The oral mucosa and other areas of the skin were unaffected.

The boy was diagnosed with postinflammatory perioral hyperpigmentation due to perioral contact dermatitis. He was advised to avoid lip-licking and was prescribed a skin brightening agent containing niacinamide and arbutin, to be applied during evenings and a sunscreen to be used every morning. After two weeks of regular use, the pigmented demarcation started fading. Continued usage for three weeks resulted in disappearance of pigmentation; the results were satisfactory. 

References

1. Nouveau S, Agrawal D, Kohli M, Bernerd F, Misra N, Nayak CS. Skin Hyperpigmentation in Indian Population: Insights and Best Practice. Indian J Dermatol. 2016;61(5):487-495. doi:10.4103/0019-5154.190103
2. Baby T. Isolated postinflammatory perioral hyperpigmentation: A rare case report. Indian Journal of Multidisciplinary Dentistry. 2019;9(2):115. doi:10.4103/ijmd.ijmd_28_19