Dermatology Online Journal

Little is known about the pathophysiology of delusional infestation (DI), a psychodermatologic condition in which patients have a fixed, false belief of being infested with parasites or inanimate material in their skin, despite lack of objective evidence. Because some delusional states, such as schizophrenia and psychotic state in bipolar disorder have been found to be associated with brain structural and functional abnormalities, a literature review was conducted to summarize available data on structural and functional abnormalities that are found to be associated with DI. A review of the literature found cases of brain imaging studies in patients with primary DI, as well as patients with secondary DI. Accumulating evidence from the studies reviewed suggests that dysfunction of the fronto-striato-thalamo-parietal network may explain how delusions manifest in DI and suggest that DI has an organic etiology. Abnormalities in the striato-thalamo-parietal network may cause false sensations of infestation through dysfunction in visuo-tactile regulation, whereas abnormalities in the frontal region may impair judgement. Delusional infestation patients also exhibit increased activation of brain structures implicated in itch processing. Furthermore, patients at high risk for cerebrovascular disease who present with secondary DI may benefit from brain imaging studies to rule out brain ischemic insult.