Hypermelanosis involving the face and neck frequently poses a diagnostic challenge. 

The goal of a recent study published in the Indian Journal of Dermatology was to investigate patterns of facial melanosis in Indian skin and assess the importance of patch testing in the diagnosis of facial melanosis.

This study selected 50 consenting patients. A detailed history, along with clinical, dermoscopic and histopathological evaluation was conducted. Additionally, patch testing using the universal series, cosmetic series and photopatch were carried out.

The results showed that facial melanosis from contact dermatitis is a frequent entity among 18-70-year-olds and was common in both sexes with a male preponderance. The most common dermoscopic finding was reticular pigmented network—seen in 66% of the cases. Histopathology revealed an increased basal melanin in 56% of the cases and pigment incontinence in 26%. The commonest allergen in men was potassium dichromate while most females showed allergy to nickel. In this study, 10% of the cases elicited positive photopatch test, whereas suspected allergen patch testing was negative in all. 

Facial melanosis as a result of contact dermatitis must be differentiated from other acquired dermatological conditions causing hyperpigmentation. Hence, a detailed history of contact with allergens must be determined and should then be confirmed by patch testing.

Source: Indian Journal of Dermatology. Jul-Aug 2021;66(4):337-342. doi: 10.4103/ijd.IJD_559_19.