Diagnosis of nummular dermatitis is largely via clinical observation. Many contact sensitizers or irritants are known to cause contact dermatitis superimposed on nummular dermatitis. Cotoneaster nummularius, the nummular or coinwort cotoneaster is a species of cotoneaster. The prevalence of nummular dermatitis in the United States is approximately 2 per 1,000. Nummular keratitis is a feature of viral keratoconjunctivitis. Nummular dermatitis is one of the many forms of dermatitis. In children, nummular dermatitis is commonly confused with tinea corporis. Nummular dermatitis is characterized by chronic or relapsing itchy coin-sized ovoid-shaped red plaques.