Trigeminal trophic syndrome (TTS) is a rare condition that results from a prior injury to the sensory distribution of the trigeminal nerve. Patients typically respond to the altered sensation with self-mutilation, most often of the nasal ala. We describe 3 patients with TTS who presented with self-induced ulcerations primarily involving the scalp. Two patients developed delusions of parasitosis (DOP) based on the resulting symptoms of TTS, which is a unique association. Trigeminal trophic syndrome may occur at extranasal sites and in any branch of the trigeminal nerve. The condition should be considered when ulcers are encountered in this nerve distribution. Symptoms such as formication may mimic DOP. Trigeminal trophic syndrome may be differentiated from DOP by the restriction of symptoms and ulcerations to the distribution of the trigeminal nerve.