Chapter 66 Psychocutaneous diseases
1. How do the fields of psychiatry and dermatology overlap?
Many studies confirm that a high percentage of dermatology patients have coexistent psychiatric morbidity. Our understanding of this phenomenon remains limited. We do know that the skin and nervous system have the same embryologic origin, and that tactile stimulation is critical for full neuropsychological development, but many questions remain.
3. How often do patients with dermatologic disorders have associated psychologic morbidity?
This figure is difficult to assess; however, some studies have reported that more than 40% of all dermatologic patients have associated psychologic morbidity. Although many skin conditions are trivial, they are usually visible to the patient and often to the public. Healthy-appearing skin is a reflection of health and well-being, and abnormalities can seriously affect the patient’s happiness.
Gupta MA: Psychosomatic dermatology: is it relevant? Arch Dermatol 126:90–93, 1990.
4. What is the differential diagnosis of patients who complain that they are infested with parasites?
6. What is “delusions of parasitosis”?
These patients falsely believe that their skin is infested with parasites. They often describe insects mating, laying eggs, and crawling around in their skin. They do not admit to actually seeing the insects themselves, as they are not hallucinating. On presentation, patients may bring in specimens containing hair, lint, and even living organisms for examination (Fig. 66-1). They develop elaborate purification rituals and are often well known to pest control organizations. It is not uncommon for the delusion to be shared by other family members. This is called folie à deux.
Figure 66-1. Scale, scabs, and hair brought in by a patient with delusions of parasitosis who insists that these are parasites.
Edlich RF, Cross CL, Wack CA, Long WB 3rd: Delusions of parasitosis, Ann J Emerg Med 27:997–999, 2009.
8. How do you treat this problem?
Delusions, like hallucinations, are psychotic symptoms that are theorized to result from increased levels of dopamine in parts of the brain. Patients with delusions of parasitosis have been shown to respond to neuroleptics; in particular, the dopamine antagonist pimozide (Orap) is, historically, the commonly used treatment. However, more recent anecdotal success has been reported with other agents having fewer side effects, including risperidone, olanzapine, and escitalopram. Although, large, well-controlled, randomized trials comparing the efficacy of these drugs are lacking, these drugs are now probably the drugs of choice.
