Black hair dye dermatitis is a major cause of concealed facial melanosis in patients with dark complexion

Background Hair dye dermatitis is a common problem that is localized to the head or even generalized, and in many countries, it runs as an outbreak problem. Many patients could present with facial melanosis but without an obvious history of dermatitis. Objective To record patients with facial melanosis that was triggered by black hair dying and to highlight this concealed cause of facial pigmentation. Methods This is a cross-sectional descriptive study where 102 patients with black hair dye facial melanosis were seen during the period from 2014-2022. All patients with Fitzpatrick skin type III and IV. Full demographic features were clarified. History and examination were carried out, and skin biopsies for histopathological assessment were done in selected cases. All other causes of facial melanosis were excluded. The therapeutic trial used Mometasone Furoate 0.1% cream twice a day for one month. Results A total of hundred two patients with facial melanosis were analyzed; their ages ranged from 30-60 years with a mean of 50 years,70 (68.6%) males and 32 (31.4%) females with a ratio of 2:1. History and examination showed that all patients were applying black hair dye from 0.5-4 years and the duration of facial pigmentation ranged from 1-5 years. Patients mentioned some itching of the face, while others mentioned a history of an erythematous rash of the face in the early course of the disease. On examination, all patients revealed deep brown to dark hyperpigmentation of the face, neck, and hands. Woods light examination gave no contrast, while histopathological assessment showed an increase in the melanin stores both in the epidermis and dermis. Topical therapy with Mometasone Furoate, 0.1% cream, gave a very satisfactory response by lightening the skin. Conclusion Black hair dye is an important cause of facial melanosis that is often overlooked and confused with other causes of facial melanosis, commonly diffuse lichen planus actinicus, where its therapy will be very difficult unless hair dying is prevented. Therapy with mometasone Furoate 0.1% cream showed a satisfactory result.