Pigmented contact dermatitis: A brief review

Optical whiteners

Osmundsen^[10] reported an epidemic of PCD in Copenhagen secondary to optic whiteners in washing powder. A mixture of two pyrazoline derivatives, Tinopal CH 3566 was found to be responsible for the pigmentation. Similarly, Pinol-Aguade et al.^[11] reported optic whitener as a cause of PCD in nearly half of their patients.

Azo dyes

Naphthol AS, an azoic dye used in textiles was reported to be the culprit allergen in an epidemic outburst of PCD.^[12] Patients with relatively darker complexion developed PCD whereas classical eczema was seen in fair-skinned individuals. Sudan I, vaccine red,^[13] and brilliant lake red R^[14] are few dyes reported to induce PCD. Isolated cases with exposure to insoluble cutting oils,^[15] PPD,^[16] and other substances are also described.^[2]

Fragrances

Nakayama^[17] reported fragrances like benzyl salicylate, hydroxy-citronellal, geraniol, and cinnamic alcohol and essential oils (e.g., ylang-ylang and Jasmine absolute)^[18] to induce PCD. Mathias^[19] studied a patient with recurrent facial dermatitis with subsequent facial hyperpigmentation and chromium hydroxide in commercial toilet soap was found to be the allergen. Prurigo pigmentosa-like contact dermatitis has also been reported secondary to chrome in detergent, though the link is not well established.^[20]

Kwong et al., reported limonene, a terpene derived from citrus fruits used for its fresh lemon aroma, to be the allergen responsible for the antiperspirant-led PCD of the axilla. Though limonene on its own has low sensitization potential, hydroperoxides formed from its oxidation are potent sensitizers.^[21] PCD with airborne contact allergens has been reported with whitening dyes, packaging adhesive tapes, and musk ambrette present in incense.^[18]

Formaldehyde

Pigmented cosmetic dermatitis was reported in a 51-year-old white woman who wore a leather watch strap and paratertiary-butylphenol-formaldehyde resin was found to be the culprit allergen in the strap.^[22]

Cosmetics

In a recent study by Sharma et al.,^[8] cosmetics were found to be the commonest culprit for PCD in India. Out of the 152 relevant patch test reactions with cosmetic allergens, the most frequent culprits were preservatives (n = 71, 46.7%), hair dye ingredients (n = 47, 31%), fragrances (n = 25, 16.4%), emulsifiers/surfactants (n = 5, 3.2%), and vehicles (n = 2, 1.3%).

Various individual components in cosmetics have been reported to result in PCD in the literature. A solvent, benzyl salicylate used as odorant, fixative, and sunscreen leads to PCD which usually takes a longer time to resolve (sometimes more than 1 year).^[23] PCD to lipsticks has been reported with coal tar dyes like CI 15800 brilliant lake red and other 1-phenylazo-2-naphthol derivatives. Other allegens reported causing lip PCD to include ester gum,^[24] isopalmityl diglyceryl sebacate,^[25] ricinoleic acid^[26] and dipentaerythritol fatty acid ester (dipentaerythritolesters with hexahydroxy stearate and rosinate).^[27] Musk moskene produces a sweet fragrance with a creamy powder note in cosmetics. Hayakawa et al., reported a patient with slate brown pigmentation after using a cheek rouge containing musk moskene.^[18]

Many cultural practices followed by specific population can result in PCD. ‘Kumkum’ is usually applied by women to the center of the forehead or on the frontal hair parting to represent the marital status in India. Among patients of kumkum dermatitis, Nath and Thappa^[28] reported 76% and 24% of patients to have PCD and allergic contact dermatitis, respectively.^[29] Clinically either brown or slate gray colored pigmentation suggestive of lichen planus pigmentosus was found without overt dermatitis. “Kumkum” commonly contains brilliant lake red R, Sudan I, aminoazobenzene, canaga oil, fragrances, groundnut oil, tragacanth gum, turmeric powder, thimerosal, gallate mix, PPD, Kathon CG, benzotriazol, tert-butyl hydroquinone, parabens, azo dyes, mercury, and lead sulphide.^[30]

The incidence of hair dye-induced skin reactions is increasing as many people dye their hair periodically for cosmetic reasons. PPD was reported to be the most frequent sensitizer in a retrospective study by Samanta et al.^[31] In a Korean study by Woo et al.,^[31] henna was found to be associated with slate-greyish dyspigmented patches over the hairline. Patch testing performed in patients with ACD and PCD following hair dye use revealed that ACD was associated with PPD whereas natural henna powder was associated with PCD.^[33] In spite of being considered safe, henna can also lead to immediate and delayed-type hypersensitivity reactions.^[34] In a recent study by Bishnoi et al.,^[35] it was found that in a total of 108 patients with acquired dermal macular hyperpigmentation (ADMH), the frequency of positive patch tests was higher within "own hair colors" than that with PPD in Indian standard series. There are several components in the hair dyes like primary intermediates or precursors (PPD, toluene-2,5-diamine), developers (hydrogen peroxide, which may contain ammonia), and couplers (resorcinol, 3-aminophenol, and 4-aminophenol). It has been reported that though PPD is not an allergen on its own but the oxidation products of PPD like 40-nitroaniline and 4,40-azodianiline are strong sensitizers.

Next to hair dyes, one of the common cosmetics used to cause PCD among patients with skin of color is the fairness cream. Lavender absolute, musk mix, cetyl alcohol, thimerosal, sorbic acid, germall 11, and benzyl salicylate are the most common allergens in fairness creams.^[8]

Medications turned into allergens

Inui et al.,^[36] studied hyperpigmentation occurring as a complication of diphenylcyclopropene in alopecia areata totalis (AAT) and alopecia areata universalis (AAU). About 11 (5.91%) of the 186 patients had hyperpigmentation and all these patients had severe AA. The patients with pigmentation showed poor response to contact immunisation. Garcia-Gavin et al., reported paradoxical hyperpigmentation in a patient who applied kojic acid for lightening of lentigines on arms, and a patch test with kojic acid 1% aqua was positive.^[37] Single case reports of PCD secondary to minoxidil and green tea have also been reported.^[38] Common allergens implicated in PCD have been listed in Table 2.

Clinical features

The onset of pigmentation in PCD is insidious and usually with no preexisting inflammation. The clinical symptoms are usually mild and because of the slower clearance of dermal pigment the lesions persist for a longer time in spite of the withdrawal of the allergen. The skin manifestations can be diffuse or patchy brown hyperpigmentation on the cheeks, ears (outer surface, helix, and lobule), temporals and preauricular regions, nape of the neck, and the upper half of the back, inframammary area, and arms [Figure 1].^[41] The pigmentation can be of different shades of black, purple, or blue-black. Erythematous macules or papules, slight erythema, and exfoliation suggest a mild contact dermatitis can be observed rarely.^[3] Sometimes the allergen responsible can produce pigmentation where the contact is maximal like PCD secondary to textiles commonly involve the front of the thighs and axillae (without involving the vault, Figure 2). The clinical manifestations can overlap with entities such as lichen planus pigmentosus and ashy dermatosis.^[1]

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Figure 1:

Clinical image of pigmented contact dermatitis showing diffuse bluish-black pigmentation of the face. (a) Involvement of the helix and ear lobule can be appreciated; (b) Prominent involvement of forehead, temples, ear and neck with relative sparing of central face.

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Figure 2:

A case of pigmented contact dermatitis to textile dyes showing prominent involvement of axilla with central sparing.

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Patch and photo-patch testing in PCD

Patch testing is done with standard series, cosmetic series, and fragrance series comprised of indigenous allergens to which the local population is more susceptible. The readings are to be taken at 48 hrs and on the 7th day. The International Contact Dermatitis Research Group (ICDRG) scoring system is helpful in interpreting the results as given in Table 3. In photo-patch testing, two sets of patch tests would be applied over the upper back and after 24 hours the readings will be recorded. Later only one set will be exposed to 14 J/cmsq of UVA. The second reading would be taken at 48 hours following UVA exposure (day 3). According to the standard photo-patch criteria, the photoallergic reaction is labeled when only the UVA exposed side has a positive result. If there is patch test positivity on both the sides but with an equal grading or with UVA exposed site having >1+ positivity then a diagnosis of contact dermatitis or contact dermatitis with photoaggravation is given respectively [Figure 3]. In the case of PCD, delayed brown pigmentation can also be seen on patch testing. Based on the history or examination of the patient the clinical relevance of a patch test positivity can be labeled as per no/past/present relevance. Samanta et al.,^[30] performed patch testing in PCD patients with Indian cosmetic series. About 79% of patients showed patch test positivity with significance in 71%. The colorant PPD was reported as the most common allergen (37%), followed by fragrances (18%), preservatives (15%), anti-microbial (11%), and emulsifier and anti-oxidants (each 8%). In a retrospective analysis by Sharma et al.,^[8] cetrimonium bromide, gallate mix, thimerosal, and skin lightening creams were found to be the common allergens. The studies done in patch testing of PCD have been summarized in Table 4.

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Figure 3:

Photo-patch testing in a case of pigmented contact dermatitis showing increased positivity (3+ with blistering) over irradiated site compared to the patch tested site (2+) to hair dye suggestive of photoaggravation. Patch and photo-patch testing with PPD shows negative results in comparison to own hair colors.

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If patch testing is negative or equivocal, due to the low concentration of the allergen in cosmetic and fragrance series there is a role for repeated open application test (ROAT). In case of an equivocal result in ROAT done on the forearm, the test can be repeated with the cosmetic of the patient over affected areas or face.^[9]

Quantitative assessment and quality of life in PCD

Acquired dermal macular hyperpigmentation area and severity index (DPASI), is a tool utilized in the assessment of disease severity in ADMH quantitatively.^[44] The face and the neck are divided into six different segments and using dermoscopy the severity is graded and multiplied by the surface area involved with a maximum score of 40.

Cosmetic disfigurement in PCD can lead to significantly low self-esteem, anxiety and depression, and social stigma. In a cross-sectional study of 52 patients, it was found that the mean score of the Dermatology Life Quality Index (DLQI) and Melasma Quality of Life Scale (MELASQOL) were high in patients with PCD upon comparison with melasma and healthy controls. The lower educational status and long duration of the disease were associated with poor quality of life.^[45] Dabas et al., reported that in a total of 100 patients with ADMH, 18.7%, 24.1%, and 14.3% had anxiety, depression, and somatoform disorder respectively along with a positive correlation between severity and the point prevalence of anxiety and depression.^[46]