Background: Prurigo nodularis is a highly pruritic condition, often considered as a reaction pattern to chronic pruritus. Variety of diseases that induce chronic pruritus may lead to the development of  a vicious itch–scratch–cycle resulting in therapy refractory nodular lesions. Our aim is to study the demographics, clinical pattern and associated dermatological or systemic causes of chronic pruritus in patients with prurigo nodularis.

Methods: A Descriptive observational study is conducted among 50 patients of prurigo nodularis.  History, detailed examination and relevant investigations for common associated conditions of chronic pruritus were done and data are subjected to statistical analysis.

Observations: Fifty patients enrolled in the study with a male female ratio of 1.17:1. The commonest site affected is the extensor aspect of legs. Most common association is atopic diathesis with an earlier age of onset of the disease than the rest. The other conditions associated were popular urticaria, allergic contact dermatitis, varicose eczema, scabies and urticaria. Interestingly, We found two cases of chronic dermatophytosis who developed prurigo nodularis. The systemic factors for chronic pruritus in our patients were diabetes, hypothyroidism and HIV infection. 4% of the patients had a positive family history. Serum total IgE levels is found to be raised in 84% of the patients and correlated with disease severity.

Conclusion: About 54% of our patients with prurigo nodularis had an underlying causative factor for chronic pruritus. As prurigo nodularis is chronic and refractory condition, it is important to treat the underlying pruritus in order to control the disease.

Keywords: prurigo, prurigo nodularis, etiology, associated diseases, chronic pruritus, serum IgE levels.

1. Hyde JN. Prurigo nodularis. In: Hyde JN, Montgomery FH, A Practical Treatise on Diseases of the Skin for the Use of Students and Practitioners. 8th ed.Philadelphia and New York: Lea Brothers & Co; 1909. p. 174–5.
2. Ständer S, Greaves M. Pruritus, Prurigo and Lichen Simplex. In: Christopher.G, editor. Rook’s textbook of Dermatology. 9th ed. Chichester: John Wiley & Sons, Ltd; p. 83.13-18.
3. Metz M, Ständer S. Chronic pruritus – pathogenesis, clinical aspects and treatment. J Eur Acad Dermatol Venereol. 2010;24:1249–60.
4. Iking A, Grundmann S, Chatzigeorgakidis E, Phan NQ, Klein D, Ständer S. Prurigo as a symptom of atopic and non-atopic diseases: aetiological survey in a consecutive cohort of 108 patients. J Eur Acad Dermatol Venereol 2013; 27: 550–557.
5. Tan WS, Tey HL. Extensive prurigo nodularis: characterization and etiology. Dermatology. 2014;228(3):276-80.
6. Tanaka M, Aiba S, Matsumura N, et al. Prurigonodularis consists of two distinct forms: early-onset atopic and late-onset non-atopic. Dermatology .1995;190:269–76.
7. Miyachi Y, Okamoto H, Furukawa F, Imamura S. Prurigo nodularis: a possible relationship to atopy. J Dermatol (Tokyo) 1980; 7: 281–283.
8. Winhoven SM, Gawkrodger DJ. Nodular prurigo: metabolic diseases are a common association. Clin Exp Dermatol. 2007;32:224–225.
9. Bohme T, Heitkemper T, Mettang T, Phan NQ, Stander S. Clinical featuresand prurigonodularis in nephrogenic pruritus. Hautarzt 2014; 65:714–720.
10. Bhalerao A, Mannu GS. Management of pruritus in chronic liver disease. Dermatol Res Pract 2015; 2015:295891.
11. Stumpf A, Stander S. Neuropathic itch: diagnosis and management. Dermatol Ther 2013; 26:104–109.
12. Magand F, Nacher M, Cazorla C, Cambazard F et al. Predictive values prurigo nodularis and herpes zoster for HIV infection and immunosuppression requiring HAART in French Guiana. Trans R Soc Trop Med Hyg 2011; 105: 401–404.
13. O'Loughlin S, Diaz-Perez JL, Gleich GJ, Winkelmann RK. Serum IgE in Dermatitis and Dermatosis: An Analysis of 497 Cases. Arch Dermatol. 1977;113(3):309–315.

Kannambal K

Associate Professor, Department of Dermatology Venereology and Leprosy, Rajah Muthiah Medical College & Hospital, Annamalai University, Chidambaram, India – 608002