Prurigo nodularis is a chronic condition of uncertain etiology. Although exact prevalence is unknown, it is most commonly seen in patients aged 45 years and older and seems to be more common in women and in people of color. Patients present with one or more (usually multiple) discrete, severely pruritic nodules that mostly appear on the extensor surfaces of extremities and anterior areas of the thighs and legs. The lesions are rarely seen on the face. The lesions are triggered by repetitive rubbing or scratching of discrete areas of the skin. Pruritus is described as severe and distressing and can become worse with heat, sweating, or irritation from friction. It may alternatively be induced by repetitive picking or rubbing of nonpruritic skin.
Prurigo nodularis may be secondary to skin conditions associated with pruritus, such as atopic dermatitis and xerosis, as well as systemic conditions associated with generalized pruritus without a primary skin rash, such as psychiatric conditions, eating disorders, HIV infection, iron-deficiency anemia, diabetes mellitus, gluten enteropathy, thyroid disease, renal or hepatic impairment, malignancies, and others. In most cases, the etiology of pruritus is unknown. Studies have suggested that prurigo nodularis may be a form of subclinical small fiber neuropathy and that Th2 cytokines play an important role in its pathogenesis.
Lesions are firm dome-shaped, smooth-topped, or crusted nodules. Their size ranges from several millimeters to 1-2 cm, and they often enlarge slowly over time. Lichenification of the lesions is often not present.
Patients with this disorder may have an increased risk of various general medical conditions.
Prurigo nodularis is a condition of extremely itchy papules (small, solid bumps) or nodules (solid, raised bumps that are firm to the touch) on the skin that may have a scab from scratching or picking. The lesions range in size but are generally smaller than a thumbnail. They can enlarge slowly over time. In some cases, there may be no itching, but uncontrollable picking or rubbing is the cause.
It is sometimes associated with another chronic skin condition, such as generalized itching or atopic dermatitis (eczema). It can also occur in people will illnesses that involve severe itching.
Prurigo nodularis can be a long-term (chronic) problem that lasts for many years. When an underlying medical or psychiatric condition is the cause of itching, it often resolves with appropriate treatment of the condition.
Who’s At Risk
Prurigo nodularis can occur in people of all ages, but it mainly affects middle-aged to elderly people and is more common in women.
This condition can also occur in people with psychiatric disorders, eating disorders, HIV infection, kidney or liver problems, and cancers because all of these illnesses can involve severe itching.
Prurigo nodularis can also occur with other itchy skin conditions such as eczema.
Signs & Symptoms
There may be many small or large bumps on the skin, especially on the trunk, backs of the arms, thighs, and legs. The bumps appear as sores, and they may be covered with a layer of scaly or crusted skin. There is often no rash on the areas of the body that are difficult to reach, such as the mid-upper back.
In lighter skin colors, the lesions may be any shade of pink or red. In darker skin colors, redness can be difficult to see or may appear purple, dark brown, or gray. Areas of intense itching usually appear darker (hyperpigmented) than other parts of the skin. This hyperpigmentation is more common and often lasts longer in darker skin colors.
Scratching the bumps can lead to open sores, where bacteria can enter and cause an infection.
The best self-care tip for people with prurigo nodularis is to avoid scratching the lesions. Scratching releases histamine in the skin that makes them itch even more. This, in turn, can lead to a vicious cycle of more scratching and more itching, known as the "itch-scratch cycle."
Keeping your nails short, wearing gloves at night, and wearing bandages over the bumps that itch the most can limit the damage from scratching.
Using soothing creams (such as those containing menthol, pramoxine, or camphor) applied once or twice a day can help control the itch, as can over-the-counter antihistamines (like diphenhydramine [Benadryl]) taken at night.
For mild cases of prurigo nodularis, over-the-counter hydrocortisone cream (eg, Cortaid) can be applied. Usually, though, stronger steroids prescribed by a medical professional are needed.
When to Seek Medical Care
See a medical professional if the itch-scratch cycle seems unbearable, you can't stop picking, or if there is a possibility of infection.
Having prurigo nodularis may suggest that there is another disease going on in the body that needs attention and treatment.
The medical professional may explain that even with treatment, prurigo nodularis is a challenging condition to control because of the severe itching involved and the difficultly with stopping the picking or rubbing.
There are several options for treating prurigo nodularis.
Corticosteroids – Topical steroid creams or ointments can be prescribed for the lesions.
Steroids come in different strengths, and your health care professional will prescribe based on the severity and location of your skin lesions. Your medical professional may recommend putting tape or bandages already containing the steroids over the bumps.
Oral medication, injections, and other treatments:
Oral antihistamines and other medication classes can be used to help control the itching and constant picking.
Steroid medications can be injected directly into the bumps, which can be helpful in reducing the itch.
Cryotherapy is a treatment that involves freezing the bumps to make them appear smaller.
Phototherapy is a treatment that uses light similar to sunlight. This therapy has been used to treat lesions that are all over the body (widespread). It can require several sessions with your dermatologist to see results.
Dupilumab (Dupixent), which is injected under the skin (subcutaneously), may be used for severe cases.
Antibiotic ointments or an oral antibiotic may be used if any of the affected areas become infected.
Antidepressants and antiepileptics may lead to some improvement.