Delusional Parasitosis

Aka: Delusional Parasitosis, Delusions of Parasitosis, Delusory Parasitosis, Ekbom's Syndrome, Dermatophobia, Parasitophobic Neurodermatitis, Parasitophobia, Entomophobia

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