Morgellons in dermatology.

Delusional parasitosis (DP) is the most frequent delusional disorder in dermatology. In DP there is a fixed belief of a usually skin-related invasion or infestation by a number of alleged infectious species (usually parasites and bacteria), whose identity has varied over the decades. Since 2002 worldwide an increasing number of patients have complained of unverifiable fibers and filaments in or on the skin, associated with numerous nonspecific complaints (arthralgias, altered cognitive function and extreme fatigue). This entity has been named "Morgellons disease" by the patients themselves, although medical evidence for its existence is lacking. As an example, we discuss a 55-year-old woman who complained of Morgellons disease and was treated as if she had DP. Currently the delusional assumption of infestation with Morgellons should be considered as a new type of DP with some kind of inanimate material. We therefore recommend in case of DP including Morgellons the use of the broader term "delusional infestation".