The mother of a healthy 11-year-old boy brings him to the office for help to clear a rash that has persisted around his mouth for 3 months. Although the boy rarely licks his lips, he does not use lip products and has not changed his dental products.
Diagnosis: Lip-licking dermatitis
Etiology and epidemiology
Lip-licking dermatitis is a form of chronic irritant contact dermatitis caused by repeated exposure of the lips and perioral area to saliva.1,2 This condition is commonly found in young children, but it can also be seen in adolescents and adults, and it is typically worse in the winter months.2
The dermatitis results from repetitive cycles of maceration and drying from repeated licking of the lips, which damages the epidermal barrier causing irritation and inflammation.3 Stratum corneum is the outermost semi-impenetrable layer of the skin that retains moisture and constitutes the major physical barrier of the skin. Cells in this layer, corneocytes, bind water with the aid of surface lipids and envelope proteins.4
Frequent wet-dry episodes erode surface lipids causing disruption to the corneocytes and lead to the loss of skin water content and the release of inflammatory cytokines, including tumor necrosis factor alpha and interleukin-1.1,3 This translates to the classic ring of dry and inflamed skin observed on clinical presentation.
Well-demarcated and symmetric erythema of the upper and lower cutaneous lip with the involvement of the vermillion border is characteristic of lip-licking dermatitis. The inside of the mouth and areas beyond reach of the tongue are spared. It can present with overlying red papules, scaling, crusting, or fissures. In skin of color, a hyperpigmented or hypopigmented ring is more typical than erythema. Symptoms may include dryness and burning, and, in contrast to allergic contact dermatitis, itching is typically modest or absent.1-3