Prurigo Simplex

Synonyms

Prurigo.

Epidemiology

Rather common disease, standing alone or associated with atopic dermatitis.

Definition

Group of dermatoses with many causes, all featuring intense pruritus followed by reactive crusted papules (prurigo = itchy crust).

Aetiology & Pathogenesis

Prurigo seems to develop in individuals, who overreact to pruritus (itch).

Causes: systemic triggers of pruritus, idiopathic, atopic constitution. Chronic, persistent disease with proliferation of peripheral sensory nerves.

Prurigo simplex and prurigo nodularis seem to be different stages of a common disease.

Signs & Symptoms

Pruritus, small sero-papules (beginning) and excoriations with symmetrical distribution of secondary prurigo lesions on the extensor surfaces of the extremities, neck, lower trunk, and buttocks. Typically, patients present with widespread dome shaped papules, which are intensely itchy leading to sleep deprivation.

Localisation

Extremities, trunk (interscapular area is usually spared!).

Classification

Acute, subacute and chronic forms.

Laboratory & other workups

Exclude underlying metabolic diseases, malfunctions of kidney and liver, hematologic disorders and parasitic infestations. Blood: Eosinophils, IgE (DD: prurigo type of atopic dermatitis). Psychological/psychiatric consultation recommended (67% abnormal).

Dermatopathology

Acute to chronic dermatitis with epidermal acanthosis and spongiosis, strong inflammatory cell infiltrate. Sensory nerve proliferation.

Course

Chronic, symptoms often persist for months to years.

Complications

Superinfections of excoriated lesions.

Diagnosis

Clinical features.

Differential diagnosis

Atopic dermatitis (prurigo variant), scabies, dermatitis herpetiformis and bullous pemphigoid (prurigo variant).

Prevention & Therapy

Secondary prevention: Exclude underlying disorders and avoid scratching.

Topical: corticosteroids, capsaicin cream, narrow band UVB, PUVA
Systemic: sedative antihistamines. In prurigo type of atopic dermatitis: Dupilimumab.

1.5.6 Prurigo Simplex