Prurigo Nodularis

Key Points
Common skin condition which typically affects the lower arms and legs or scalp
Exact cause is unknown, but may be related to dermatitis or underlying systemic conditions
Consists of the formation of numerous nodules which are firm, rough-surfaced and accompanied by severe itching.

Prurigo nodularis is an uncommon skin condition which typically affects the lower parts of the arms and legs, but may also involve the face, palms and torso. The condition consists of the formation of numerous nodules which begin as mildly itchy, red bumps. Fully developed lesions are firm and have a rough, warty texture. The condition is accompanied by severe, sometimes intense itching. Scratching may cause crusting and scaling of affected skin, and make lesions vulnerable to secondary infection. Nodules may be few in number, or up to 200 individual lesions may form. The condition is often persistent for years.

The exact cause of prurigo nodularis is unknown. It is thought the condition may be related to certain forms of dermatitis, asthma, and hay fever or underlying systemic conditions such as renal failure, Iron deficiency, gluten enteropathy, and HIV. The condition typically presents during adulthood and may affect anyone regardless of ethnic or gender group.

Differential Diagnosis (Other conditions with similar appearance)
Acute Febrile Neutrophilic Dermatosis
Hypersensitivity Vasculitis (Leukocytoclastic Vasculitis)
Aphthous Stomatitis
Impetigo
Behcet disease
Insect Bites
Chancroid
Sporotrichosis
Churg-Strauss Syndrome (Allergic granulomatosis)
Squamous Cell Carcinoma
Ecthyma
Venous Insufficiency
Ecthyma Gangrenosum
Verrucous carcinoma
Herpes simplex
Wegener granulomatosis

Diagnosis
Key Points
Diagnosis based on the characteristic appearance of the affected area
Skin biopsy may be performed to confirm diagnosis and rule out other conditions

Prurigo nodularis is typically diagnosed based on the characteristic appearance of the affected area. A skin biopsy may be performed to confirm the diagnosis and to rule out similar appearing conditions.

Treatment
Condition is extremely resistant to treatment
Many therapies are available, with varying degrees of effectiveness
Severe cases may require more aggressive systemic therapies
OTC Options: emollients, antihistamines, topical Antibiotics, coal tar preparations

Prurigo nodularis is extremely resistant to treatment. Often, the goal of treatment is to relieve symptoms. Use of OTC remedies such as emollients, antihistamines, topical antibiotics, and coal tar preparations may assist in relieving itching, dryness, secondary infection and inflammation. Topical medications including steroid, calcipotriol, and capsaicin creams may also be prescribed for this purpose, in addition to therapies such as corticosteroid Injections, cryotherapy, and pulsed dye laser therapies. In severe cases, aggressive systemic therapies may be recommended, including phototherapy, systemic steroids, thalidomide, ciclosporin, retinoids, and naltrexone.