II. Epidemiology
- More often seen in women over age 50 years
III. Classification
- Monosymptomatic Hypochondriacal Psychosis
IV. Symptoms
- Patient convinced of Parasite infestation
V. Signs
- Matchbox Sign
- Patient presents container with purported Parasite
- Focal erosions on exposed areas of arms and legs
- Results from attempts to pick bugs from skin
VI. Differential Diagnosis
- Schizophrenia
- Major Depression with Psychosis
- Bipolar Disorder with manic Psychosis
- Vitamin B12 Deficiency
- Multiple Sclerosis
- Syphilis
- Cerebrovascular Accident
-
Hallucination of Insects crawling on skin (formication)
- Drug Intoxication (e.g. Cocaine, Amphetamine)
- Drug Withdrawal (e.g. Alcohol Withdrawal)
VII. Labs (consider for differential diagnosis evaluation)
- Complete Blood Count (CBC)
- Serum chemistry panel
- Thyroid Stimulating Hormone (TSH)
- Rapid Plasma Reagin (RPR)
- Urinalysis
- Urine Drug Screen
VIII. Management
- Confirm diagnosis
- Rule-out true parasitic cause of symptoms
- Evaluate for differential diagnosis as above
-
General measures
- Establish patient's trust
- Listen
- Communicate empathy and sensitivity
- Avoid offending or further isolating patient
- Consider psychotherapy
- Establish patient's trust
-
Pimozide (Orap)
- Initial dose: One-half of a 2 mg tablet qd
- Titrate dose: Increase dose by 1 mg/week to 4-6 mg qd
IX. References
- Habif (1996) Clinical Derm, Mosby, p. 67-8
- Stephens (1999) Am Fam Physician 60(9):2507-8 [PubMed]
- Koo (2001) Am Fam Physician 64(11):1873-8 [PubMed]