Psychogenic Pruritus

Synonyms

Somatoform itch/pruritus; psycho-somatic pruritus; non-organic itch.

Epidemiology

Approximately 6% of dermatology clinic patients suffer with the condition. The frequency in the general population is likely to be lower.

Definition

An itch disorder where organic causes have been excluded and where itch is the primary symptom and where psychological factors affect triggering, intensity, aggravation, or persistence of the itch (modified from the French Psycho-Dermatology Group 2018).

Aetiology & Pathogenesis

The aetiology of this condition is poorly understood but there is an interplay of neurological and psychological factors resulting in the symptoms.

Signs & Symptoms

The itch is persistent and often unbearable. Secondary changes such as erythema and erosions/ulcerations and finally scars may occur.

Localisation

The condition may be generalised or circumscribed. Localised forms may particularly affect the genitalia or scalp.

Classification

None.

Laboratory & other workups

The condition can only be diagnosed by excluding other causes, so laboratory tests are mandatory. Systemic conditions to exclude are diabetes mellitus, thyroid dysfunction, iron deficiency, uraemia, cholestasis, Hodgkin and non-Hodgkin lymphomas, erythropoietic protoporphyria. Primary skin diseases to exclude by examination or tests include dermatitis herpetiformis, scabies, urticaria, atopic dermatitis and other parasitic infections.

Dermatopathology

Biopsy is seldom necessary, apart from excluding another primary skin condition (e.g. cutaneous lymphoma). Histological findings would be non-specific, with excoriations and potentially prurigo nodules.

Course

Usually chronic.

Complications

Psychogenic pruritus is often accompanied by sleep disturbance, which may further exacerbate the condition. The patient’s quality of life is invariably severely reduced. Scarring and secondary infections may also occur.

Diagnosis

Sensitivity should be shown when discussing the diagnosis with the patient.

3 compulsory criteria:

Localised or generalised itch without primary skin lesion.
Rash present for > 6 weeks.
No somatic cause.

7 optional criteria:

Temporal relation between symptoms and a life event.
Variations in intensity with stress.
Diurnal variation.
Predominance of symptoms at rest.
Associated psychological disorder.
Pruritus improved by psychoactive medications.
Pruritus improved by psychotherapy.

Differential diagnosis

Symptomatic pruritus associated with systemic or cutaneous diseases including scabies, adverse reaction to medications (especially opioids), neuropathic itch, delusional infestations, diffuse mastocytosis and mast cell activation syndrome.

Prevention & Therapy

Topical antipruritics e.g. menthol, crotamiton.

Systemic antipruritics e.g. antihistamines (hydroxyzine, cetirizine) or antihistamines with other psychotropic effects (doxepin, mirtazepine).

Psychotherapy and psychopharmaceuticals initiated by a psychiatrist e.g. fluoxetine and olanzepine.

Special