What is the classification of prurigo (itching disease)?

From the Guidelines

Prurigo classification is primarily based on clinical presentation and duration, dividing into acute, subacute, and chronic forms, with treatment depending on the type and underlying cause. The classification of prurigo can be complex, with various types including prurigo nodularis, prurigo simplex, and prurigo pigmentosa, each with distinct characteristics and treatment approaches 1.

Key Classification Types

• Acute prurigo: develops rapidly with intensely pruritic papules and vesicles, often due to insect bites or contact dermatitis, typically resolving within weeks.
• Subacute prurigo: persists for weeks to months with excoriated papules and nodules, commonly associated with atopic dermatitis or drug reactions.
• Chronic prurigo: lasts for months to years with firm, hyperkeratotic nodules resulting from persistent scratching, including prurigo nodularis.

Treatment Approaches

Treatment of prurigo depends on the type but generally includes:

• Topical corticosteroids, such as clobetasol 0.05% twice daily for 2-4 weeks.
• Antihistamines, like hydroxyzine 25mg three times daily.
• Addressing underlying causes, which can include iron deficiency, iron overload, lymphoma, polycythaemia vera, solid cancers, uraemia, liver disease, neuropathy, and psychological or emotional factors, as outlined in the British Association of Dermatologists' guidelines for the investigation and management of generalized pruritus in adults without an underlying dermatosis, 2018 1.

Underlying Causes and Specific Treatments

• Generalized pruritus due to iron deficiency may be treated with iron replacement.
• Uraemic pruritus may be managed with BB-UVB, and renal transplantation is considered a definitive treatment.
• Hepatic pruritus may be treated with rifampicin as first-line, followed by cholestyramine and sertraline.
• Psychogenic pruritus may benefit from NB-UVB and psychosocial interventions. Breaking the itch-scratch cycle is essential for effective management, often requiring a combination of treatments targeting both inflammation and neurogenic pathways involved in chronic pruritus 1.

From the Research

Prurigo Classification

• Prurigo is a reactive, hyperplastic skin condition characterized by pruritic papules, plaques, and/or nodules 2.
• The temporal classification of prurigo includes acute/subacute and chronic disease (≥ 6 weeks), with different clinical variants, synonymies, and underlying etiological factors 2.
• Prurigo can be classified based on clinical forms and causes, with disease name classifications such as prurigo nodularis, prurigo chronica multiformis, and prurigo (not otherwise specified) 3.
• Chronic prurigo is a distinct disease characterized by chronic pruritus, a lengthy scratching behaviour, and the presence of pruriginous lesions, with clinical subtypes including papular, nodular, plaque, umbilicated, and linear prurigo 4.

Clinical Variants

• Prurigo nodularis is a chronic disease characterized by intensely pruritic, raised, nodular lesions 5.
• Prurigo chronica multiformis is a clinical variant of prurigo, with multiple forms of lesions 3.
• Other clinical variants of prurigo include papular, plaque, umbilicated, and linear prurigo 4.

Diagnosis and Treatment

• The diagnosis of prurigo involves a complete review of systems, considering potential systemic diseases, and assessment of disease severity, including disease burden and pruritus intensity 5.
• Treatment of prurigo should be selected based on a patient's clinical presentation, comorbidities, and response to prior treatments, and should address both neural and immunologic components of pruritus 5.
• Non-systemic forms of treatment for prurigo nodularis include topical corticosteroids, topical steroid-sparing agents, and phototherapy 6.