What is the condition characterized by a single medically unexplained symptom?

The condition characterized by a single medically unexplained symptom is known as Conversion Disorder. This disorder manifests when a person experiences neurological symptoms, such as motor or sensory dysfunction, that cannot be attributed to a known medical condition. These symptoms can include paralysis, weakness, or abnormal gait, and typically arise in response to psychological stress or trauma. The hallmark of Conversion Disorder is that the symptom is not deliberately produced or feigned, distinguishing it from other conditions where physical symptoms may be present but are influenced by underlying psychological factors or intentions.

In this context, it's important to recognize that Hypochondriasis, now more commonly referred to as Illness Anxiety Disorder, involves an excessive worry about having a serious illness despite minimal or no symptoms. Somatization Disorder, on the other hand, involves multiple medically unexplained symptoms across various bodily systems. Factitious Disorder includes the intentional production or feigning of symptoms for the purpose of assuming the sick role. Thus, the unique aspect of Conversion Disorder is the occurrence of a single, unexplained symptom that arises in the absence of conscious intent or malice, making it the correct choice in this scenario.