Pigmented contact dermatitis (PCD) is characterized by non-eczematous pigmentation associated with contact sensitizers, usually without any active or preceding pruritus and erythema. PCD was first described by Riehl, who identified patients with brown to gray facial pigmentation concentrated on the face most commonly associated with sensitizing chemical such as cosmetics, fragrances, and textiles.
This is a case of a 48-year-old female Filipino who presents with blue-grey to brown patches on the forehead of 1-year duration with no significant pathologic history. Clinical examination, dermoscopy and histology were consistent with a variant of pigmented contact dermatitis known as Riehl melanosis. Since anamnesis was unremarkable, patch testing was done to identify the contact allergen triggering the symptom. Results obtained a positive reaction to nickel, potassium dichromate, and textile dye.
Treatment includes the elimination of trigger factors, hence the importance of patch testing in the investigation of its cause. Alongside adequate photoprotection, a combination treatment of 1,064 nm Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) laser, 20% tricholoacetic acid (TCA) peel and oral retinoids, were found safe and effective in the management of facial melanosis. Three-dimensional imaging and dermoscopy
were utilized to obtain a more standard and objective pre- and post-treatment comparison.