Neuropathic Pruritus as a Precursor to Delusional Parasitosis in Multiple Sclerosis: A Proposed Clinical Trajectory and Case Report.

Multiple sclerosis (MS) is a chronic demyelinating disorder of the central nervous system that is associated with a range of neuropsychiatric complications, including depression, anxiety, and cognitive impairment. Delusional parasitosis is a rare and underrecognized manifestation in patients with MS. It is characterized by a fixed false belief of infestation with parasites or other organisms despite the absence of supporting medical evidence. In some cases, the condition may be preceded by chronic neuropathic pruritus, which can contribute to the development of somatic delusions. A 76-year-old woman with a longstanding history of MS developed persistent generalized pruritus and underwent multiple dermatologic evaluations, all of which yielded negative results. Despite the absence of objective findings, she received numerous courses of antiparasitic and anti-inflammatory treatments over three years. Her symptoms progressed to a fixed belief of infestation, which persisted despite repeated disconfirmation. The condition was associated with substantial psychosocial consequences, including isolation and the dissolution of long-term relationships. This case illustrates a possible clinical progression from neuropathic pruritus to delusional parasitosis in MS. The findings underscore the importance of early recognition to potentially prevent progression, as well as the need for coordinated care involving primary care, neurology, dermatology, and psychiatry.