Delusional parasitosis treated by atypical antipsychotic and selective serotonin reuptake inhibitor: a case report

Delusional parasitosis (DP) is an uncommon psychiatric disorder. Patients suffering from this disorder have the fixed false belief of being infested by a parasite. Because of this condition, patients mainly consult with dermatologists or general practitioners. They are often reluctant to see a psychiatrist and to take treatment with antipsychotics because of their belief. The following describes the case of a woman who has the particularity that the DP started a few days after sertraline interruption. This situation raises the question of the impact of the sertraline interruption on pruritus and its role as a trigger of DP.

Case report description and research on medline, pubmed with the keyword: delusional parasitosis, Ekbom syndrome, pruritus, SSRI.

Any other pathology that could explain the patient's symptomatology was excluded which allows us to diagnose this patient with DP. The disappearance of the symptoms was obtained with 200 mg of sertraline and 2 mg of risperidone. It appears that pruritus can be favored by cutaneous dryness due to age and anxiety. Symptoms of discontinuation of SSRIs may include anxiety and paresthesia.

The main hypothesis explaining the onset of DP would be the raise of paresthesia followed by the interruption of sertraline (discontinuation symptom) on a favorable field, which means an elderly woman of an anxious nature and having cutaneous dryness. It therefore seems necessary to discuss the discontinuation symptoms at the initiation of a treatment for this kind of patient to avoid false interpretations of skin symptoms such as paresthesia or itching.