Self-induced trauma to the nails.

Both frequent and rare deformities of the nails have been reported that are due to self-inflicted damage. Some of these disorders may be confused with common diseases such as psoriasis, lichen planus, onychomycosis, or industrial injury. Awareness of the common patterns, inspection of the periungual tissues, observation of the patient's attitude toward his or her nail disorder, and inclusion of self-trauma in the differential diagnosis will lower the incidence of ineffective treatments and unnecessary laboratory tests.