Patients labeled with delusions of parasitosis compose a heterogenous group: a retrospective study from a referral center.

BACKGROUND: There are few diagnostic tools available to the dermatologist to help in the diagnosis of patients with delusions of parasitosis (DOP).
OBJECTIVE: We sought to find differences in presentation and clinical course between patients who received a final diagnosis of DOP and those who received a final diagnosis of a primary medical condition or other psychiatric disorder.
METHODS: We performed a retrospective chart review of patients referred with a diagnosis of DOP. Each patient received a final consensus diagnosis.
RESULTS: In all, 47 patients were included in the study. Patients reporting bugs were more likely to be given a final diagnosis of delusional disorder or found to have a medical diagnosis, whereas patients noting fibers were more likely to have a somatoform disorder. A review of systems can be helpful in making a final diagnosis. Patients referred to the clinic for DOP were 300 times more likely to require a physician to contact the hospital's legal counsel compared with other patients in the practice. LIMITATIONS: The retrospective nature of the study resulted in limited laboratory testing and psychiatric evaluation in some patients. Many of the patients may have been inappropriately referred to the DOP clinic because of other psychiatric comorbidities.
CONCLUSION: Patients referred to this practice as "delusional" had a heterogeneous final diagnosis. The chief symptom of the patient was predictive of the patient's final diagnosis. The use of written questionnaires may be helpful. These patients have a greatly increased risk of requiring the physician to seek legal counsel.