INTRODUCTION
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.
CASE REPORT
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.
DISCUSSION
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
