Patients with delusional disorders hold a fixed, false belief that is nonbizarre in nature.1 Delusions of parasitosis (DOP) is a somatic subtype of delusional disorder, also known as monosymptomatic hypochondriacal psychosis. It has been reported to be more common in females (2:1) and in patients older than 45 years (88%).2,3 The management of DOP has been discussed extensively in the medical literature.4,5 However, many patients have been labeled with DOP who do not meet the diagnostic criteria or who present with additional somatic complaints. These cases are a unique therapeutic challenge for dermatologists and psychiatrists alike and have not been thoroughly studied or reported. We present a patient referred for DOP who benefited substantially from antidepressant therapy.
A 62-year-old female was referred to the dermatology service at University of Texas Southwestern in Austin, TX, by her primary dermatologist for DOP. She had suffered from this condition for 18 months and was seen previously by 2 primary care physicians and a dermatologist. The patient was well dressed and organized during the interview. She told the attending physician that she was coming in for "something crawling in [her] skin." She wondered if she had Morgellons disease but noted that she didn't see any fibers or threads on her skin. Further discussion with the patient elucidated that she did not, in fact, have fixed beliefs regarding the source of her crawling sensations and that she had considered that maybe she was "just crazy." The patient noted that she felt these sensations on her face and in between her teeth. She also complained of increasing fatigue, sleeplessness, weight loss, muscle aches, and intermittent stomach cramps, for which her workup was negative. She said her friends have always said that she was so sensitive to anything on her skin that they dubbed her the "Princess and the Pea." She was unable to participate in social events because of a concern that someone would "see something coming out of [her] skin." The patient's medical history was unremarkable, and she had received all age-appropriate screenings. She was widowed 2 years previously. Full skin exam was unremarkable except for 3 superficial excoriations on her face. Laboratory testing was normal, including complete blood count, complete metabolic panel, thyroid-stimulating hormone, ferritin, human immunode"ciency virus testing, urinalysis, and urine drug screen.
This patient did not fit into the classic diagnosis of DOP because of her lack of a fixed false belief. In addition, this patient showed somatic symptoms such as sleep impairment and psychomotor retardation and met criteria for both depression and anxiety. No infection was found on her skin; however, her physicians validated her suffering and offered to help her "cope better." She was started on citalopram at 10 mg, increasing to 20 mg a day in 1 week. During her second follow-up visit (4 weeks after starting the citalopram), she complained that she still felt something like bugs on her skin. The dermatologist offered to discontinue the citalopram. She immediately broke in, "No way! If it wasn't for that citalopram, I would have killed myself!" The medication was slowly increased to 40 mg a day, with gradual resolution of her fatigue and muscle aches. The sores have all healed. The patient said that she still felt stinging sensations at times, but they were less bothersome and she could go about her daily activities. The patient has now been on the medication for 2 years and has no somatic complaints.
Since this original patient, we have treated 5 more patients with a similar presentation and have found citalopram to be the most efficacious agent.
Patients with suspected DOP have a broad differential diagnosis, including skin-based or systemic medical conditions and several kinds of psychiatric disease. Four-year data from our dermatology clinic revealed that 13% of patients referred for DOP had a clear medical explanation (eg, dermatitis, dementia, polypharmacy, neuropathy), 30% were found to have a delusional disorder, and 17% were found to have obsessive picking of their skin. In 40% of the patients seen, no medical cause could be found, but they all demonstrated symptoms of anxiety and depression.6