Abstract

This article reports progressive facial hyperpigmentationin a 47-year-old woman. The pigmentation had first appeared about a year back after she had used a skin lightening product on her face and neck. The hyperpigmented rash had initially appeared on her chin, which had then spread to theforehead, cheeks and around her mouth.

On physical examination, numerous, discrete to confluent, fine, brownish-gray macules were observed on the forehead, cheeks and around the mouth. The lightening product she had used, was found to contain octyl methoxycinnamate – a potential contact sensitizer.

Dermoscopy and histopathological examination aided in the confirmatory diagnosis of Riehl melanosis (RM). The patient was prescribed hydroquinone 4% once daily at night for an initial two-week period, coupled with a sunscreen in the daytime. Thereafter, she was advised to use topical tretinoin 0.05% after sunset and sunscreen every 3 hours in the daytime, for six months.

This treatment resulted in overall improvements in her hyperpigmented lesions and provided a lightening effect of the skin. After 12 months, the pigmented areas seemed to be inconspicuous and matched the adjacent skin. The only side effect was mild skin dryness which resolved with the use of moisturizing sunscreen in the daytime.

Introduction

Riehl melanosis – abnormal hyperpigmentation involving the face and neck regions, is an acquired low-grade allergic contact dermatitis to fragrance and other cosmetic products. The common facial sitesaffected are –forehead, zygomatic, and/or temporal regions. The disorder is known to predominantly affect Asians.

This skin condition was first identified during the first World War by Riehl, who had speculated wartime food substitutes and poor-quality flour to be the contributing factors. Now, it is known that a majority of cases of RM occurs due to exogenous agents—and can be categorized as contact dermatitis. Thus, RM is deemed as a pigmented contact dermatitis (PCD). Ultraviolet (UV) ray exposure may also play a role in PCD since hyperpigmentation is often photo-localized; some of these causative chemicals are known as ‘photosensitizers’.

Common causative allergens are:

Case Report

A 47-year-old female complained of progressive facial hyperpigmentation.

The lady reported that the pigmentation had first appeared about a year back after she had used a skin lightening product for three months. The hyperpigmented rash had initially appeared on her chin; thereafter, within six months, it spread to the forehead, cheeksand around her mouth.

On physical examination, numerous, discrete to confluent, fine, brownish-gray macules were observed on the forehead, cheeks and around the mouth. Dermoscopy showed diffuse erythema, telangiectasia, multiple brown and gray dots/granules, pseudonetwork pigmentation andperifollicular whitish halo. Histopathological examination revealed basket-weave stratum corneum, hypergranulosis, colloid bodies, dense inflammatory infiltrates within the dermo-epidermal junction, increased melanin deposition, pigment incontinence and melanophages.The lightening product she had used, was found to contain octyl methoxycinnamate – a potential contact sensitizer. The patient was diagnosed with RM/PCD. The patient was prescribed hydroquinone 4% once daily at night for an initial 2-week period,coupled with sunscreenin the daytime. Thereafter, she was advised to use topical tretinoin 0.05% after sunset and sunscreen every 3 hoursin the daytime. Six months of this therapy conferred remarkable improvements in the hyperpigmented areas. This treatment rendered a lightening effect on the pigmented areas of the skin and also lead to an oval improvement in wrinkling and roughness of the skin. The patient did not report of any adverse effect apart from mild skin dryness, which could be controlled by the use of a moisturizing sunscreen during the day. On follow up after 12 months, the pigmented areas had almost disappeared and appeared as the same color as the surrounding skin. The patient compliance was good and she was satisfied with the outcome.

Discussion

Tretinoin – a derivative of vitamin A (retinol), is also commonly known as Retin-A and all-trans retinoic acid (ATRA). Tretinoin can be used systemically as well as topically for various indications.Topical tretinoin is available in gels, creams and lotion formulations. Their FDA approved indications are:

• Topical application for treatment of acne vulgaris
• Adjunctive palliative treatment of photoaging:

0 Fine facial wrinkles

0 Facial skin roughness

0 Facial mottled hyperpigmentation

Tretinoin acts by binding of retinoic acid receptors (RARs) alpha, beta and gamma along with retinoid X receptors (RXRs) by blocking inflammatory mediators, and thereby increasing theproduction of procollagen to augment collagen type I and III formations.This agent is efficacious as an acne medication, owing to its ability to modify the abnormal follicular formation that occurs due toexcessive keratinization of epithelial cells.² When used on photodamaged skin or hyperpigmented lesions, this drug has demonstrated overall improvement in the appearance of the lesions – with respect to skin lightening, reduced wrinkling and merging of the pigmented spots with the surrounding skin.³

Topical tretinoin should be used as a thin layer once dailyat after sunset or at bedtime, on the affected areas.²

Conclusion

This case demonstrates the efficacy of topical tretinoin use in treating long-standing RM/PCDlesions in a middle-aged woman. This disorder usually affects the facial skin and is common in individuals with a history of cosmetic usage.

Here, a 47-year-old female presented with progressive facial hyperpigmentation since once year, which was triggered after the use of a skin lightening product.The lightening product she had used, contained octyl methoxycinnamate – a potential contact sensitizer. The hyperpigmented lesion had initially appeared on her chin, which had then spread to the forehead, cheeks and around her mouth. Clinical examination revealed numerous, discrete to confluent, fine, brownish-gray macules on the forehead, cheeks and around the mouth.Dermoscopy and histopathological examination confirmed RM/PCD. The lady was successfully treated with a two-week course of hydroquinone 4% once daily at night and sunscreen in the daytime, followed by six months’applicationof tretinoin 0.05% after sunset, coupled with sunscreen use every 3 hours during the day. The therapy was well-tolerated and rendered satisfactory results with respect to overall improvement and lightening or macules, 6-month and 12-month follow ups.

References

1. Daadaa N, Ben Tanfous A. Riehl Melanosis. [Updated 2020 May 30]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from:https://www.ncbi.nlm.nih.gov/books/NBK557437/
2. Yoham AL, Casadesus D. Tretinoin. [Updated 2020 May 30]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK557478/
3. Weinstein GD, Nigra TP, Pochi PE, et al. Topical tretinoin for treatment of photodamaged skin. A multicenter study. Arch Dermatol. 1991;127(5):659-665.