Dermatologists with specialised experience and training should be empowered to prescribe antipsychotic medication to patients with delusional infestation, a European consensus statement argues.

The recommendations, formed through the Delphi method and involving input from 21 dermatologists, 14 psychiatrists and 2 tropical medicine specialists, emphasised the importance of collaboration between dermatologists and psychiatrists for the management of patients with this rare psychiatric condition [link here].

Delusional infestation is characterised by a fixed belief that the body or skin is infested with an animate or inanimate material, despite a lack of medical evidence this is the case.

Patients report tactile hallucinations and abnormal skin sensations, and while they are treated with antipsychotic drugs as first-line therapy many struggle with adherence to treatment. Their management between dermatology and psychiatric models of care can be disjointed.

Two online e-Delphi rounds led to consensus on 20 statements related to the best practice management of delusional infestation, including:

• Examination of materials presented by the patient, including specimens and photos, must be completed as part of the diagnostic process,
• Blood sampling and urine toxicology should be completed to exclude organic diagnosis and identify any recreational drug use,
• Psychiatric treatment should happen concurrently with any treatment of actual skin conditions, if they are present,
• Dermatologists with experience and training should be able to prescribe antipsychotics, which should be offered as first-line treatment,
• Dermatologists should work collaboratively with psychiatrists and other health providers to manage patient care, and
• CBT has been shown to have no additional treatment value for patients with this condition.

Writing in JEADV, dermatologist at Amsterdam UMC Dr Patrick Kemperman and colleagues said their work revealed the conceptual challenges that persist in providing care to these patients.

Dr Patrick Kemperman

“DI is not classified as a distinct disorder in either DSM-5 or ICD-11,but is subsumed under somatic-type delusional disorder (in DSM-5) within the broader category of delusional disorders,” they said.

In their consultation, experts discussed the need for greater inclusivity and clarity when discussing the condition with patients.

“Multiple respondents highlighted that DI encompasses not only beliefs of infestation by organisms but also by inanimate objects, such as fibres, particles or bodily debris,” the authors said.

The issue of how best to communicate about the condition also attracted mixed opinions, however. For example, no consensus was reached on whether a clinician should explicitly use the label “delusional infestation”.

“Instead, many panellists advocated symptom-focused language and individualised communication strategies tailored to the patient’s level of insight and receptivity,” the panel said.

Overall, thoughtful use of language and collaboration between specialties were the most important elements for this patient group, they said.

“These results lay the groundwork for future guideline development and affirm the need for ongoing research in this complex condition.”