Schizoaffective disorder Quiz: Ace Your Exams

A 25-year-old man is brought to the physician by his partner to evaluate an unpleasant feeling on his skin. The patient tells the physician that he feels like “bugs are climbing all over my skin.” This sensation is deeply distressing to the patient, and he is constantly trying to scratch his skin, even at bedtime, often disrupting his sleep. He has not experienced visual or auditory hallucinations. His partner is also concerned because the patient has lost 25-lb over the past six months. The patient has no history of mental disorders or any other diseases. The partner denies experiencing a similar sensation and has no difficulty sleeping at night. Temperature is 37.0°C (98.6°F), pulse is 110/min, respirations are 19/min, and blood pressure is 160/94 mmHg. Physical examination of the patient reveals evidence of skin picking and bruises on the skin, most prominent on the forearms and antecubital region. In addition, the nose appears dry with some residual blood. The patient is easily irritated when asked questions throughout the encounter. Which of the following is the most likely cause of this patient’s presentation?