Delusional infestation in clinical practice over a period of two decades

Patients presenting with cutaneous symptomatology may in fact suffer from underlying psychiatric conditions. Individuals diagnosed with delusional infestation (DI) have a fixed false belief of being infested with certain organisms or objects.

To analyse clinical features of subjects with DI who were admitted to the tertiary dermatology ward.

A retrospective analysis concerning DI patients hospitalized between 1997 and 2019 was carried out. The emphasis was put on the duration of symptoms, psychiatric symptomatology (including the "specimen sign"), comorbidities as well as therapy.

We gathered data regarding 21 consecutive patients with DI. The mean age of subjects was 65.2 ±13.3 years, the majority were females (76.2%). The mean time span between the disease onset and diagnosis was 1.9 ±1.7 years. Previous psychiatric consultations were attended by 57.0% of patients. The specimen sign was present in 47.6% of cases, whereas the most common suspected causative factors were described as worms (52.4%), unspecified parasites (42.9%), "something" (33.3%) and flies (19.0%). Primary delusional disorder was diagnosed in 76.2%, followed by shared delusional disorder and secondary delusional disorder of organic origin (9.5% each). Risperidone monotherapy was initiated in 61.9% of patients. In total, only 33.3% of patients attended the follow-up visit.

DI features a wide spectrum of clinical signs and symptoms. Risperidone remains the drug of choice in the majority of cases. Successful management of each DI case requires collaboration between dermatologists and psychiatrists and still remains a major challenge.