DermDx: Dark Skin Patches

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A 34-year-old African woman is referred for evaluation of pigmentary changes affecting her face. She has been applying a skin lightening cream to dark areas on her cheeks for approximately 1 year. Four months ago, she noticed ‘spots’ of darkened and lightened skin at the sites of application. She is in good health and takes no oral medications. Examination reveals striking hyperpigmentation dotted with 2- to 4-mm hypopigmented macules.

Exogenous ochronosis (EO) is a cutaneous disorder characterized by blue-black or slate-gray paradoxical hyperpigmentation resulting from the prolonged use of certain topical agents, most commonly hydroquinone. Other agents that can induce similar pigmentation changes include phenol and resorcinol. The disorder...

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Exogenous ochronosis (EO) is a cutaneous disorder characterized by blue-black or slate-gray paradoxical hyperpigmentation resulting from the prolonged use of certain topical agents, most commonly hydroquinone. Other agents that can induce similar pigmentation changes include phenol and resorcinol. The disorder is clinically and histologically similar to its endogenous counterpart, alkaptonuria.1 The latter is an inherited disorder accompanied by progressive arthritis.

This condition is most common in Black patients from South Africa, affecting a significant percentage of the population. Case studies also document EO occurrence in White, Asian, and Hispanic individuals.2 The disorder is often disfiguring and may impact the patient’s social and emotional well-being.

The initial stage of the disorder is erythema, which eventuates in hyperpigmentation and confetti-like hypopigmentation. In addition to the face, other areas of involvement may include the sides and back of the neck, extensor surfaces of the extremities, and back. Associated findings include striae atrophicae and colloid milium.3,4

The diagnosis of EO is usually based on clinical examination. The addition of histopathology and dermoscopy may aid in the diagnosis and differentiate this condition from melasma.5,6 The EO lesion under dermatoscopy will show a variation of grey to blue and/or brown or black amorphous to globular areas. A specific sign on histology is the finding of yellow-brown curvilinear, banana-shaped ochronotic fibers.7

It was originally believed that only high concentrations of hydroquinone could cause EO; however, more recent reports describe the development of EO after the use of lower concentrations such as 2% preparations. In addition, the percentage of hydroquinone quoted by a manufacturer may not necessarily represent the true concentration of hydroquinone in a product.8

Skin-bleaching practices, such as using skin creams and soaps to achieve a lighter skin tone, are common throughout the world. The cosmetic reasons behind this practice often have deep historic, economic, sociocultural, and psychosocial roots.9 The authors emphasize the possibility of EO cases being misdiagnosed as melasma treatment failure. We also emphasize the risk of indiscriminate topical application of hydroquinone-containing compounds without adequate medical supervision.

Nejib Doss, MD, is a dermatologist practicing at the Centre Urbain Nord in Tunis, Tunisia; Safi Eldin E. Ali, PhD, is director of Dermatology and Venereology Council, Sudan Medical Specialization Board (SMSB), Sudan; Seemal R. Desai, MD, FAAD, is assistant professor in the Department of Dermatology, The University of Texas Southwestern Medical Center in Dallas; Stephen Schleicher, MD, is director of the DermDox Dermatology Centers in Pennsylvania, associate professor of medicine at Geisinger Commonwealth Medical College, and clinical instructor of dermatology at Arcadia University and Kings College.

References

1. Bhatar PA, Zawar VP, Godse KV, Patil SP, Nadkarni NJ, Gautam MM. Exogenous ochronosis. Indian J Dermatol. 2015;60(6):537-543. doi:10.4103/0019-5154.169122

2. Tan SK. Exogenous ochronosis in ethnic Chinese Asians: a clinicopathological study, diagnosis and treatment. J Eur Acad Dermatol Venereol. 2011;25(7):842-850. doi:10.1111/j.1468-3083.2010.03904.x

3. Bongiorno MR, Arico M. Exogenous ochronosis and striae atrophicae following the use of bleaching creams. Int J Dermatol. 2005;44(2):112-125. doi:10.1111/j.1365-4632.2005.02346.x

4. Gönül M, Cakmak SK, Kilic A, Gonul U, Heper AO. Pigmented coalescing papules on the dorsa of the hands: pigmented colloid milium associated with exogenous ochronosis. J Dermatol. 2006;33(4):287-290. doi:10.1111/j.1346-8138.2006.00069.x

5. Khunger N, Kandhari R. Dermoscopic criteria for differentiating exogenous ochronosis from melasma. Indian J Dermatol Venereol Leprol. 2013;79:819-821. doi:10.4103/0378-6323.120741

6. Romero SA, Pereira PM, Mariano AV, Francesconi F, Francesconi VA. Use of dermoscopy for diagnosis of exogenous ochronosis. An Bras Dermatol. 2011;86(4 Suppl 1):S31-34. doi:10.1590/s0365-05962011000700007

7. Simmons BJ, Griffith RD, Bray FN, Falto-Aizpurua LA, Nouri K. Exogenous ochronosis: a comprehensive review of the diagnosis, epidemiology, causes, and treatments. Am J Clin Dermatol. 2015;16(3):205-212. doi:10.1007/s40257-015-0126-8

8. Morand JJ, Ly F, Lightburn E, Mahé A. [Complications of cosmetic skin bleaching in Africa]. Med Trop (Mars). 2007;67(6):627-634

9. Kourouma S, Gbery IP, Kaloga M, et al. [Cutaneous depigmentation in black female population for cosmetic purposes: results of a KAP survey conducted in Abidjan (Ivory Coast)]. Pan Afr Med J. 2016;24:159. doi:10.11604/pamj.2016.24.159.831

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