Continuing medical education
Prurigo nodularis: Epidemiology and clinical features

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Prurigo nodularis (PN) is a chronic inflammatory skin disease characterized by intensely pruritic, hyperkeratotic nodules that favor the extensor surfaces of the extremities and the trunk. In addition to its significant impact on quality of life, many patients with PN are recalcitrant to therapy because there are currently no therapies approved by the US Food and Drug Administration. In the first article of this 2-part continuing medical education series, we describe the broader epidemiology, patient demographics, physical examination findings, and symptoms to aid in the timely recognition and diagnosis of PN. Furthermore, we quantify the burden of comorbidities in PN by discussing the broad spectrum of systemic diseases and mental health conditions that have been associated with this condition. The second article of this 2-part series focuses on the pathogenesis of PN and provides detailed algorithms for comprehensive work-up and management.

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Key points

  • Prurigo nodularis is a chronic, pruritic inflammatory skin disease characterized by numerous symmetrically distributed hyperkeratotic nodules most commonly on the extensor surfaces of the extremities and trunk

  • Prurigo nodularis is diagnosed clinically, although biopsy specimens of lesional skin can show thickened, hyperplastic dermal nerve fibers with decreased density of intraepidermal nerve fibers

Prurigo nodularis (PN) was first described by Hyde in 1909,1 who detailed the hyperkeratotic

Key points

  • Prurigo nodularis most commonly affects middle-aged adults and tends to be diagnosed more frequently in females compared with males

  • Patients with skin of color, including African Americans, are also at increased risk

Prevalence

PN is a relatively rare condition, with an estimated prevalence of 72 per 100,000 individuals in an epidemiologic study of US adults 18 to 64 years of age who have health care insurance.13 Given the variability in the coding of PN in medical claims data, this figure may be a

Key points

  • Prurigo nodularis is associated with increased rates of mental health, endocrine, cardiovascular, and renal disorders, as well as HIV and malignancy

  • The burden of systemic comorbidities in prurigo nodularis often exceeds that of other inflammatory skin disorders (ie, atopic dermatitis or psoriasis)

A variety of comorbidities associated with PN have been identified through case series and epidemiologic studies. Knowledge of associated comorbidities can help guide the provider in the comprehensive

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    Funding sources: Dr Kwatra received grant funding from the Skin of Color Society and is a recipient of the Dermatology Foundation Medical Dermatology Career Development Award.

    Date of release: December 2020.

    Expiration date: December 2023.

    Conflicts of interest: Dr Kwatra is an advisory board member for Pfizer Inc, Regeneron Pharmaceuticals, and Menlo Therapeutics and has received grant funding from Pfizer Inc and Kiniksa Pharmaceuticals. The other authors involved with this journal-based CME activity have reported no relevant financial relationships with commercial interest(s).

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