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National Skin Centre
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Definition
Prurigo nodularis (PN) is a distressing condition characterized clinically by the
presence of chronic intensely itchy nodules. It usually presents as multiple
excoriated nodules on the extensor surfaces of the limbs and occurs secondary
to itching and rubbing. Its etiology is unknown but it is widely assumed to be a
cutaneous reaction pattern to repeated rubbing or scratching caused by pruritus
of various origins. It should be diagnosed only after all the other known causes
have been excluded.
Contributing factors
1. Atopy – 65 to 80% of patients are atopic
2. Insect bite reactions – 20% may start after an insect bite
3. Infections – Hepatitis C1, Helicobacter pylori2 and HIV3 have been reported as
infectious etiologies.
4. Malignancy – has been associated with gastric carcinoma4.
Clinical features
- Occurs in any age, but mainly from 20 to 60 years old
- Individual lesions are hard, globular nodules 1 to 3 cm in size
- Crusts and scales may cover the excoriated lesions
- Lesions are usually grouped and may be numerous
- Predilection for the extensors of the limbs, but he face and trunk can be
affected
- Patients distressed by crises of severe pruritus
Differential diagnosis
1) Pemphigoid nodularis
2) Epidermolysis bullosa dystrophica
3) Insect bite reactions
4) Perforating folliculitis
History and physical examination
1. Presence of itch and duration of symptoms. Please refer to therapeutic
guidelines on pruritus for evaluation of pruritus.
2. History of scratching/rubbing of lesions
3. Photoaggravation or photodistribution – actinic prurigo
4. Presence of vesicles/blister formation – DH, EBD
5. Drug history
6. Systemic review – weight loss, bowel changes
7. Other medical history – eg. Helicobacter pylori infections, Hepatitis status, HIV
Investigations
1. FBC
) Need for further investigation should be guided by
2. U/E/Cr
) clinical suspicion. Please refer to therapeutic guidelines on
3. LFT
) pruritus.
4. Patch testing – A patch test should be ordered in cases where a contact
allergy is suspected clinically. A study at Mayo clinic5 showed that 25 of 32
patients had relevant patch test. Avoidance help clear five patients, along with
topical steroids.
5. Skin biopsy – if diagnosis is in doubt and rule other differential diagnosis.
Management
General management: The patients should be given general advice to avoid
scratching and educated on the fact that scratching exacerbates the lesions.
Patients should be advised to keep their nails short., ice
Other measures: may consider wearing mittens, especially at nights
First line treatment
1) Antihistamines – eg. hydroxyzine, chlorpheniramine
3) Topical steroids - eg ½S to F/S Betnovate Ung or cream
4) Intralesional steroids injection – eg. triamcinolone 10 to 40 mg/ml may be used
monthly but it may not be applicable due to the large number of lesions. The
amount injected at each site is 1 mg and should not exceed 5 mg and the total
dose injected should not exceed 30 mg.
5) Cryotherapy – 2 weekly to be review after 2 to 3 months of treatment.
Second line treatment
Topical treatment
1) topical calcipotriol – In a study of 10 patients treated with either calcipotriol6
(50ug/g Ung) or betamethasone valerate (0.1%), statistically significant reduction
in the number of lesions was noted after 2 weeks of calcipotriol, while it took 8
weeks for similar improvement on the betamethasone treated side.
2) Superpotent steroids – eg Dermovate. Should be used with caution and side
effects of skin thinning and atrophy should be monitored closely.
3) Capsaicin cream7 – reported to be effective in 33 patients treated with
capsaicin cream (0.025% to 0.3%), 4 to 6 x/day for 2 weeks to 10 months.
Pruritus returned in 16 patients after 2 months of discontinuation. It is not
available in the NSC pharmacy.
4) Use of Occlusive membranes eg. Plasters. Four patients treated with
duoderm pads applied over the lesion (changed weekly) had clearance of their
nodules.8
Systemic treatment
1) Oral doxepin
2) phototherapy – NBUVB 3x/week for 2 to 3 months may be of benefit. PUVA
may be considered as a 2nd line treatment. Please refer cases to the photo-clinic.
2) Systemic steroids – may be of benefit in acute flares. Long-term use should be
limited because of side effects of treatment.
Third line treatment
1) Thalidomide9 – there are many case reports on the effectiveness of
thalidomide in treatment of prurigo. Dose of thalidomide: 200 – 400 mg/day for 6
to 14 months have been reported to be effective. Relief of pruritus usually within
2-3 weeks after starting treatment.
2) Cyclosporin10 – cyclosporin in doses of 3.4 to 4 mg/kg/day X 36 and 24 week
respectively reported to be effective in 2 cases.
3) Azathioprine11 – dose of 50 mg bid reported to be effective in reduction of
lesion count and size in 1 patient.
Miscellaneous
Other treatment options which have reported to be of benefit include:
1) Naltrexone12 – 9 of 17 patients helped significantly with Naltrexone (50mg/day
for 1 to 14 months). Naltrexone decreased pruritus 70-100% with healing of the
lesions. Not available in NSC pharmacy.
References:
1. Neri S, Raciti C, D’Angelo G, Ierna D, Bruno CM. Hyde’s prurigo nodularis and
chronic HCV hepatitis. J Hepatol 1998; 28(1): 161-4.
2. Neri S, Ierna D, D’Amico RA, Giarratano G, Leotta C. Helicobacter pylori and
prurigo nodularis. Hepatogastroenterology 1999; 46(28):2269-72.
3. Matthews SN, Cockerell CJ. Prurigo nodularis in HIV infected individuals. Int J
Dermatol 1998 Jun; 37(6): 401-9.
4. Funaki N, Ohno T, Dekio S et al. Prurigo nodularis associated with a case of
advance gastric cancer: report of a case. J Dermatol 1996 Oct 23(10): 703-707.
5. Zelickson BD, McEvoy MT, Fransway AF. Patch testing in prurigo nodularis.
Contact dermatitis 1989; 20:321-325.
6. Wong SS, Goh CL. Double-blind, right/left comparison of calcipotriol ointment
and betamethasone ointment in the treatment of Prurigo nodularis. Arch
Dermatol. 2000 Jun;136(6): 807-8.
7. Stander S, Luger T, Mertze D. Treatment of prurigo nodularis with topical
capsaicin. J Am Acad Dermatol 2001; 44:471-8.
8. 12 Meyers LN. Use of occlusive membrane in the treatment of prurigo
nodularis. Int J Dermatol 28:275-276.
9. Alfadley A, Al-Hawsawi K. Treatment of prurigo nodularis with thalidomide: a
case report and review of the literature. Int J Dermatol May 2003; 42(5): 372-375
10. Berth-Jones J, Smith SG, Graham-Brown RA: Nodular prurigo responds to
cyclosporin. Br J Dermatol 1995;132:795-799.
11. Lear JT, English JSC, Smith AG: Nodular prurigo responsive to azathioprine.
Br J Dermatol 1996;134: 1151.
12. Metze D, Reimann S, Beissert S, Luger T, Efficacy and safety of naltrexone,
an oral opiate receptor antagonist, in the treatment of pruritus in internal and
dermatological diseases. J Am Acad Dermatol 1999; 41:533-539