The Role of Patch Testing with Indian Cosmetic Series in Patients with Facial Pigmented Contact Dermatitis in India

BACKGROUND: Pigmented contact dermatitis (PCD) is a non-eczematoid variant of contact dermatitis, mainly characterised by hyperpigmentation. It occurs due to contact with a low amount of allergen over a long duration of time. PCD is frequently seen in Indians but is often misdiagnosed or underdiagnosed because of the asymptomatic nature of the entity. The aetiology and the allergens implicated in PCD in the Indian subcontinent is still an enigma because of the limited studies done. MATERIALS AND METHODS: This was an institution-based cross-sectional study, done at a tertiary hospital. Patch testing with Indian Cosmetic Series was conducted in a standardised method. Readings were taken at 48 hrs/72 hrs and on the 7th day [Figure 2a and b]. The International Contact Dermatitis Research Group (ICDRG) scoring system was used to grade the readings. RESULTS: Out of the 38 biopsy proven cases of PCD, 18 (47%) showed lichenoid features, 17 (45%) showed spongiotic features, 3 (8%) showed a mixed lichenoid and spongiotic pattern. Among total 1216 (32 patches × 38 patients) patch applied, 42 (3.4%) showed positivity in 30 patients. Among allergen categories, colorant (PPD) was found to be most common (37%) followed by fragrances (18%), preservatives (15%), anti-microbial (11%) and emulsifier and anti-oxidants (each 8%). CONCLUSION: It is important to identify the allergens implicated in PCD to help in better management of the condition. Patch testing proves to be a non invasive, low cost method and its role is indispensable in identifying the correct allergen.