Prurigo Nodularis

The Chronic Itchy Bumps

Mar 15, 2009 Hanish Babu

Prurigo nodularis or nodular prurigo is a chronic, intensely itchy skin disease, characterized by hard nodules and bumps, most often on the outer aspect of the limbs.

Prurigo nodularis is an eruption of lichenified or excoriated bumps and nodules on the skin caused by intractable itching that is quite difficult to treat. It was first described by Hyde in 1909.

Causes of Prurigo Nodularis

The exact cause of prurigo nodularis (PN) is not known. Prurigo nodularis is considered to be a cutaneous reaction pattern to repeated rubbing or scratching caused by itching due to various causes. 65-80% of PN patients have history of atopy. In 20% cases, the itchy bumps appear following insect bites.

Nodular prurigo has been reported to appear in association with emotional stress, anemia, obstructive liver diseases, diabetes, chronic kidney failure, mycobacterial infection other than tuberculosis, gluten intolerance, thyroid diseases, HIV infection, lymphomas, leukemias and other cancerous growths in the body.

Some dermatologists consider prurigo nodularis as belonging to the same category as neurodermatitis or lichen simplex chronicus.

In the August 1999 issue of Journal of American Academy of Dermatology, Carolyn IJ & Stella FP reported a case of chronic Strongyloides stercoralis worm infestation presenting with prurigo nodularis and lichen simplex chronicus. The itchy skin rashes disappeared following treatment of the worm infestation. PN is at times seen in untreated cases of scabies, severe dry skin and bullous pemphigoid.

Clinical Features of Prurigo Nodularis

Prurigo nodularis occurs at all ages, but is more common between 20 to 60 years. Both sexes are equally affected.

The earliest skin lesion is a small red bump which slowly enlarge to become brownish or black, hard globular nodules and bumps. The surface may have a warty rough appearance, with the center excoriated and white, and, at times, bleeding. Severe itching excoriates the surface, which becomes crusty and scaly. The number may vary from half a dozen to hundreds and the size from 1 to 3 cms in diameter.

The itchy bumps are more commonly seen on the outer aspect of the upper and lower limbs. In severe cases face, trunk and even palms may be affected.

Prurigo nodularis run a very protracted course with the patient tormented by bouts of intense itching.

Skin Diseases That May Mimic Nodular Prurigo

• Hypertrophic lichen planus, especially in the lower legs, look similar to PN.
• Insect bite reaction
• Nodular bullous pemphigoid
• Porokeratosis
• Reactive perforating collagenosis
• Leech bites
• Multiple granular cell tumors

Treatment of Prurigo Nodularis

As mentioned, prurigo nodularis is very resistant to treatment.

1. Reduction of scratching and excoriations: sedative antihistamines, cutting nails very short, wearing cotton gloves at night and occlusion of the itchy bumps with bandages or steroid impregnated tapes will help reduce the excoriations and thickening of the skin.
2. Treatment of specific causes like renal failure, HIV infection, worm infestation, mycobacterial infection etc cures nodular prurigo associated with these diseases.
3. Intralesional steroid injections. Helpful in reducing itching and thickness, but ineffective in many patients.
4. Super potent steroids under occlusion may help, but is of limited use in nodular prurigo because of the side effects of topical steroids, if used for a prolonged period.
5. Topical capsaicin and doxepin has been found effective in some patients. Capsaicin should be applied regularly 4 to 6 times daily to prevent reaccumulation of neuropeptides which causes recurrence of the itching.
6. Tranquilizers and antidepressant medications like amytryptiline may be required to reduce the psychogenic prurigo nodularis.
7. Hypnotherapy and biofeedback mechanisms may prove helpful in some cases of nodular prurigo.
8. Systemic treatment with immunosuppressants like cyclosporine and azathioprine reduces the itchy skin bumps and rashes in severe, generalized involvement. But these have systemic side effects and are reserved for really resistant, extensive cases.
9. Topical or systemic psoralen, followed by UVA phototherapy gives good results in resistant cases of Prurigo nodularis. Narrow band UVB therapy is also effective in PN.
10. The most effective medication in treatment resistant prurigo nodularis is thalidomide, the horror drug of the 60s. This drug is quite effective in PN, but may cause peripheral neuropathy; hence a low dose therapy has been advocated. Thalidomide is not to be used in women of childbearing age group as it can cause serious congenital deformities.
11. In addition to the above, drugs like dapsone, gabapentine, systemic retinoids, and cryotherapy has also been beneficial in some cases of prurigo nodularis.

The course of prurigo nodularis is often chronic, and some patients respond very poorly to the standard therapeutic modalities. There is hope for the patients, if the exact cause could be found and specific therapies applied.

Sources

• Eczema, Lichenification, Prurigo and Erythroderma in Rook’s Textbook of Dermatology, 7th Edition, 2004
• Jaana OM et al. Mycobacteria in Prurigo Nodularis: The Cause or Consequence? J Am Acad Dermatol 1996;34:224-8

Disclaimer

The information given in this article is for educational purpose only so that patients are aware of the options available. No diagnosis should be made or treatment undertaken without first consulting your doctor. If you do so, the author or suite101 will not be responsible for any consequences. The images provided are for illustration purpose only.

The copyright of the article Prurigo Nodularis in General Medicine is owned by Hanish Babu. Permission to republish Prurigo Nodularis in print or online must be granted by the author in writing.

Prurigo Nodularis: Itchy Bumps	Nodular Prurigo: Itchy Skin Rashes & Bumps	Prurigo Nodularis: Treatment Resistant Itchy Bumps
Sedating Antihistamines Relieves Itching in PN	Prurigo Nodularis: Topical Steroids Limited Help.

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Comments

Aug 6, 2009 7:24 PM

Guest :

I have experienced PN since 2000 and in my body on the scalp of my rear neck. Also, but less frequent, PN have developed in my arms and near ankles and thighs. But again, my body part that is more evident with PN is the rear neck and on the rear of my head.
The only treatment that I go for is burning them off and removing them and stitching the sking/scalp/rear head. Just today went to my dermatologis and he removed two PN in the rear of head and stitched me up.
For me, I have come to the conclusion after ten years that is absolutely related to my nervous system, i.e - stress of all types - emotional, work/job, relationship/family.
I'm really looking forward to the near future when a cure is discovered.
Sincerely from,
Irvine, California

Aug 28, 2009 1:11 AM

Guest :

Liza
my daughter whos age is one year six months too having the same disease PN for about 8 months. ive shown her different doctors and got treatment but found no cure from all of them.could u please help me to cure my child. its so severe when she itches and scratches.

Sep 15, 2009 10:44 PM

Guest :

I have lived with NP for the last 8 years. After trying just about anything and everything from cortisone shots / tablets / methotrexate / various natural therapies i.e reflexology, homeopathy etc nothing helped. Finally I am on Cyclosporine (sandimun neoral).
For the first time in 8 years I have slept through the night - NO ITCH!! It is now 3 months and I am 99% clear, apart from some headaches which have eased I for now do not have any other side effects. Yes it sounds scary but I am closely monitored by my doctor, have frequent blood test and can honestly say WOW! YOU HAVE TO TRY AND SEE IF IT WORKS FOR YOU.....

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