Laboratory Studies

No laboratory test can help in diagnosing delusions of parasitosis; however, laboratory tests can help identify other diseases that can mimic delusions of parasitosis. Note the following:

To exclude infestation, a mineral oil preparation should be used to eliminate scabies, and a microscopic examination of skin and hair should be performed to exclude louse infestation.
Neurologic pathology due to toxins or vitamin deficiencies can be evaluated with the appropriate tests.
Tests to assess other causes of pruritus (eg, low iron level, liver or kidney disease) can be performed if clinically indicated. Examples include evaluation of the complete blood cell count; urinalysis; liver function tests; thyroid function tests; and determinations of levels of serum electrolytes and glucose, blood urea nitrogen, serum creatinine, serum vitamin B-12, folate, and iron.
Unless dermatitis herpetiformis needs to be excluded, skin biopsy is usually more useful to reassure patients of the lack of pathology than to diagnose delusions of parasitosis.
Use of cocaine, methylphenidate, or amphetamines must be ascertained, and if occurring, it should be stopped.
It is useful to examine the "proof" that the patient brings in so that one may truthfully say that the material was examined and no parasites were found. One authority anecdotally relates how he found ants in the debris and, after explaining that these arthropods did not live on or in humans, was able to give practical advice to reduce the problem.

Imaging Studies

Huber et al found striatal lesions in patients with secondary delusions of parasitosis, but not in cases of primary delusions of parasitosis.^[38]In rare cases, neurologic impairment (eg, tumors, neuritis, multiple sclerosis) can mimic the symptoms of delusions of parasitosis. Causes of such impairment should be excluded with MRI or CT scanning if they are strongly suspected on the basis of the clinical findings.

Histologic Findings

Delusions of parasitosis have no specific histologic findings. All skin changes are secondary to rubbing, scratching, picking, or other treatment attempts.

Because patients who have delusions of parasitosis are having delusions, performing biopsies on them is not useful because any finding, even if negative for parasites, will not affect the delusion.^[39]

Treatment & Management

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Author

Bettina E Bernstein, DO, DFAACAP, DFAPA Distinguished Fellow, American Academy of Child and Adolescent Psychiatry; Distinguished Fellow, American Psychiatric Association; Clinical Assistant Professor of Neurosciences and Psychiatry, Department of Psychiatry/Psychiatric Medicine, Philadelphia College of Osteopathic Medicine; Clinical Affiliate Medical Staff, Department of Child and Adolescent Psychiatry, Children's Hospital of Philadelphia; Consultant to Gemma Services, Private Practice; Consultant PMHCC/CBH at Family Court, Philadelphia

Bettina E Bernstein, DO, DFAACAP, DFAPA is a member of the following medical societies: American Academy of Child and Adolescent Psychiatry, American Psychiatric Association

Disclosure: Nothing to disclose.

Specialty Editor Board

David F Butler, MD Former Section Chief of Dermatology, Central Texas Veterans Healthcare System; Professor of Dermatology, Texas A&M University College of Medicine; Founding Chair, Department of Dermatology, Scott and White Clinic

David F Butler, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, Association of Military Dermatologists, Phi Beta Kappa, Texas Dermatological Society

Disclosure: Nothing to disclose.

Chief Editor

Glen L Xiong, MD Associate Clinical Professor, Department of Psychiatry and Behavioral Sciences, Department of Internal Medicine, University of California, Davis, School of Medicine; Medical Director, Sacramento County Mental Health Treatment Center

Glen L Xiong, MD is a member of the following medical societies: AMDA - The Society for Post-Acute and Long-Term Care Medicine, American College of Physicians, American Psychiatric Association, Central California Psychiatric Society

Disclosure: Serve(d) as a director, officer, partner, employee, advisor, consultant or trustee for: SafelyYou, Blue Cross Blue Shield<br/>book co-editor for: Wolter Kluwer, American Psychiatric Publishing Inc.

Additional Contributors

Franklin Flowers, MD Professor Emeritus, Department of Dermatology, Affiliate Associate Professor of Pathology, University of Florida College of Medicine

Franklin Flowers, MD is a member of the following medical societies: American College of Mohs Surgery

Disclosure: Nothing to disclose.

Noah S Scheinfeld, JD, MD, FAAD † Assistant Clinical Professor, Department of Dermatology, Weil Cornell Medical College; Consulting Staff, Department of Dermatology, St Luke's Roosevelt Hospital Center, Beth Israel Medical Center, New York Eye and Ear Infirmary; Assistant Attending Dermatologist, New York Presbyterian Hospital; Assistant Attending Dermatologist, Lenox Hill Hospital, North Shore-LIJ Health System; Private Practice

Noah S Scheinfeld, JD, MD, FAAD is a member of the following medical societies: American Academy of Dermatology

Disclosure: Nothing to disclose.

Delusions of Parasitosis Workup

Laboratory Studies

Imaging Studies

Histologic Findings

References

Tables

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