Callus due to dermatophagia has rarely been reported in dermatology literature. Patients with this disorder usually present with skin damage, bleeding, blistering and discoloration, especially around the fingernails. Moreover, the presence of callus on the dorsum of proximal phalanges has also rarely described in the literature of PubMed, Google Scholar and Research Gate.

We hereby describe a 16-year-old boy with bilateral calluses, on the dorsal aspects of the proximal phalanges of the forefingers. General physical examination revealed that the patient had a mental illness and a habit of biting his fingers at the affected sites for two years. We performed this report to emphasize the importance of the relationship between dermatophagia and calluses presenting on the dorsum of the proximal phalanges of the fingers as calluses are most often located on the feet and knuckles of the hands. Therefore, any patient experiencing a similar lesion to the one in our case needs a proper history taken and assessment of mental state to exclude associated psychiatric comorbidity.