Skin Biter: Dermatodaxia Revisited

Dermatodaxia describes humans who bite their skin. Previously used designations, which are less appropriate, have included chewing pads, wolf-biter, and dermatophagia. Dermatodaxia is a body-focused repetitive behavior and is classified in the category of obsessive-compulsive and related disorders. People who bite their skin may concurrently have other related disorders such as dermatillomania (also referred to as skin picking) affecting their cutaneous integument, trichotillomania (also referred to as hair-pulling) affecting their hair, and/or onychophagia (also referred to as nail-biting) affecting their nails. A man with multiple medical conditions presented for follow-up evaluation of a recently treated superficial skin infection of his abdomen. Cutaneous examination not only showed complete resolution of an abdominal abscess but also dermatodaxia involving his dorsal left index finger; the skin biting site appeared as an asymptomatic lichenified nodule with overlying scaly hyperkeratosis. Additional inquiry confirmed that for several decades he would repeatedly bite this finger. He was aware - and even demonstrated - that his skin biting caused the lesion. He also declined any interventions to alter his behavior. Similar to the patient in this report, dermatodaxia typically presents as an asymptomatic, unilateral, solitary, lichenified, callous-like, thick nodule; however, bilateral involvement or multiple biting sites or both may occur. Lesions typically occur on the forearm, hands, and fingers; on the latter site, they may or may not involve the knuckles. Physical modalities, behavior modifications, and/or pharmacologic agents may be used in the management of dermatodaxia; however, many individuals with dermatodaxia - similar to the reported man - are not only aware that the cutaneous lesion is caused by their skin biting but also do not want to entertain the possibility of initiating any intervention that might change or stop their skin biting.