9. A Lady with Facial Pigmentation

Dhiraj Kumar¹

(1)

All India Institute of Medical Sciences, Patna, India

Dhiraj Kumar

Keywords

Pigmented contact dermatitisRiehl’s melanosisAllergensFragrancesPatch test

A 36-year-old woman presented to department of dermatology with complaint of dark discoloration of face for last 2 years. She gave history of application of some cosmetic cream 2 months prior to the onset of presenting complaint. The discoloration started as a reddish patch, associated with burning sensation followed by hyperpigmentation. The nature of cream was not known to the patient. No history of pre-existing dermatosis or photosensitivity was noted. There were no other associated cutaneous and systemic co-morbidities.

On cutaneous examination, there was diffuse dark-brown to greyish-brown facial pigmentation, most pronounced on the lateral aspects of face and neck particularly concentrated on the forehead, and around the eyes (Fig. 9.1). Margins were irregular and surface was non-scaly. Oral mucosa and conjunctiva were spared. Rest of the dermatological and systemic examinations were unremarkable. Dermoscopy of the lesion showed small, discrete, brown to grey pigmented dots that do not form a net like pattern (Fig. 9.2).

../images/471276_1_En_9_Chapter/471276_1_En_9_Fig1_HTML.jpg — Figure 9.1

Hyperpigmented macules and patches on the forehead and sides of the face (Courtesy: Dr. Piyush Kumar)

../images/471276_1_En_9_Chapter/471276_1_En_9_Fig2_HTML.jpg — Figure 9.2

Dermoscopy showing small, discrete, brown to grey pigmented dots that do not form a net like pattern (Courtesy: Dr. Shekhar Neema)

Based on the history and clinical presentation, what is your diagnosis?

1.

Melasma
2.

Lichen planus pigmentosus (LPP)
3.

Pigmented contact dermatitis (Riehl’smelanosis)
4.

Exogenous ochronosis

Diagnosis

Pigmented contact dermatitis (Riehl’s melanosis)

Discussion

Pigmented contact dermatitis (PCD), also known as Riehl’s melanosis, is a non-eczematous variant of contact dermatitis. In this condition, clinical picture is dominated by acquired hyperpigmentation with little or no signs of dermatitis [1]. Osmundsen, a Danish dermatologist had first used the term “pigmented contact dermatitis” to describe an epidemic of contact dermatitis in Copenhagen which had occurred due to the optical whitener (Tinopal CH 3566) used in washing powders [2]. The unique pattern of pigmentation as seen in PCD was first noted by Riehl during World War I, but Riehl could not establish the cause and attributed the pigmentation to nutritional deficiency in wartime conditions.

The exact mechanism by which these allergens induce pigmentation is unknown. Osmundsen considered it an idiosyncratic reaction. The allergen responsible for PCD may have a special affinity for melanin, inciting an inflammatory reaction first around the melanocytes and then around the cells incorporating melanin granules [3]. Nakayama et al. hypothesized that the concentrations of allergens in commercial preparations were too low to produce spongiotic dermatitis. Instead, they produced cytolytic type of type IV allergy mainly at the basal layer of the epidermis that resulted in pigmentary incontinence [4].

Commonly implicated allergens in the development of pigmented contact dermatitis are summarized in Table 9.1 and are cosmetic allergens including red and yellow pigments, chromium hydroxide, aniline and azo dyes, bactericidal agents (carbanilides, ricinoleic acids), hair dyes, red kumkum and fragrances [5]. Textile allergens too are common culprits and include optical whiteners, dyes, textile finishes, mercury compounds, formaldehyde, and rubber components. Sometimes occupational allergens like coal tar, pitch, asphalt, mineral oil, and chromates [6].

Table 9.1

Common chemicals implicated in pigmented contact dermatitis

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