Prurigo nodularis

Prurigo nodularis (PN), also known as nodular prurigo, is a skin disease characterised by pruritic (itchy) nodules which usually appear on the arms or legs. Patients often present with multiple excoriated lesions caused by scratching. PN is also known as Hyde prurigo nodularis, Picker's nodules, atypical nodular form of neurodermatitis circumscripta, lichen corneus obtusus.

Prurigo nodularis
Pruritic papules and scattered nodules can be seen (a) on the legs, (b) on the arms and (c) on the trunk of this patient with prurigo nodularis.
SpecialtyDermatology 

Lichen simplex chronicus is a distinct clinical entity.

Signs and symptoms
  • Nodules are discrete, generally symmetric, hyperpigmented or purpuric, and firm. They are greater than 0.5 cm in both width and depth (as opposed to papules which are less than 0.5 cm). They can appear on any part of the body, but generally begin on the arms and legs.
  • Excoriated lesions are often flat, umbilicated, or have a crusted top.
  • Nodules may appear to begin in the hair follicles.
  • Nodule pattern may be follicular.
  • In true prurigo nodularis, a nodule forms before itching begins. Typically, these nodules are extremely pruritic and are alleviated only by steroids.

Causes

The cause of prurigo nodularis is unknown, although other conditions may induce PN. PN has been linked to Becker's nevus,[1] linear IgA disease, an autoimmune condition,[2] liver disease[3] and T cells.[4] Systemic pruritus has been linked to cholestasis, thyroid disease, polycythaemia rubra vera, uraemia, Hodgkins disease, HIV and other immunodeficiency diseases.[5][6] Internal malignancies, liver failure, kidney failure, and psychiatric illnesses have been considered to induce PN, although more recent research has refuted a psychiatric cause for PN. Patients report an ongoing battle to distinguish themselves from those with psychiatric disorders, such as delusions of parasitosis and other psychiatric conditions.[7][8]

Pathophysiology

Chronic and repetitive scratching, picking, or rubbing of the nodules may result in permanent changes to the skin, including nodular lichenification, hyperkeratosis, hyperpigmentation, and skin thickening. Unhealed, excoriated lesions are often scaly, crusted or scabbed. Many patients report a lack of wound healing even when medications relieve the itching and subsequent scratching.

Patients often:

  • seek treatment during middle-age, although PN can occur at any age.
  • have a history of chronic severe pruritus.
  • have a significant medical history for unrelated conditions.
  • develop liver or kidney dysfunctions.
  • develop secondary skin infections.
  • have a personal or family history of atopic dermatitis.
  • have other autoimmune disorders.
  • have low vitamin D levels.

Diagnosis

Diagnosis is based on visual examination and the presence of itching. A skin biopsy is often performed to exclude other diseases. Lesion biopsies usually show light inflammation, sometimes with increased numbers of eosinophils.[9] A culture of at least one lesion will rule out staphylococcus infection, which has been significantly linked to atopic dermatitis.[10][11][12]

Treatment

Prurigo nodularis is very hard to treat, but current therapies include steroids, Dupixent, vitamins, cryosurgery, thalidomide and UVB light. In the event that staphylococcus or other infection is present, antibiotics have proven effective, but tend to cause more harm than good for this particular disease. A physician may administer a strong dose of prednisone, which will almost immediately stop the itch/scratch cycle. However, cessation of steroids allows relapse to occur, usually within a few weeks. Horiuchi et al recently reported significant improvement in PN with antibiotic therapy.[13]

Another drug a physician may administer is Apo-Azathioprine. Azathioprine, also known by its brand name Imuran, is an immunosuppressive drug used in organ transplantation and autoimmune diseases and belongs to the chemical class of purine analogues.

Dupixent was the first medication approved by the FDA in September 2022 to treat Prurigo Nodularis.

History

Prurigo nodularis was first described by Hyde and Montgomery in 1909.[14]

See also

Notes
  1. Lockshin BN, Brogan B, Billings S, Billings S (December 2006). "Eczematous dermatitis and prurigo nodularis confined to a Becker's nevus". International Journal of Dermatology. 45 (12): 1465–1466. doi:10.1111/j.1365-4632.2006.02971.x. PMID 17184268. S2CID 32658695.
  2. Torchia D, Caproni M, Del Bianco E, Cozzani E, Ketabchi S, Fabbri P (August 2006). "Linear IgA disease presenting as prurigo nodularis". The British Journal of Dermatology. 155 (2): 479–480. doi:10.1111/j.1365-2133.2006.07315.x. PMID 16882196. S2CID 28166468.
  3. Hazin R, Abu-Rajab Tamimi TI, Abuzetun JY, Zein NN (October 2009). "Recognizing and treating cutaneous signs of liver disease". Cleveland Clinic Journal of Medicine. 76 (10): 599–606. doi:10.3949/ccjm.76A.08113. PMID 19797460.
  4. Sonkoly E, Muller A, Lauerma AI, Pivarcsi A, Soto H, Kemeny L, et al. (February 2006). "IL-31: a new link between T cells and pruritus in atopic skin inflammation". The Journal of Allergy and Clinical Immunology. 117 (2): 411–417. doi:10.1016/j.jaci.2005.10.033. PMID 16461142.
  5. Hiramanek N (July 2004). "Itch: a symptom of occult disease". Australian Family Physician. 33 (7): 495–499. PMID 15301165.
  6. Berger TG, Hoffman C, Thieberg MD (November 1995). "Prurigo nodularis and photosensitivity in AIDS: treatment with thalidomide". Journal of the American Academy of Dermatology. 33 (5 Pt 1): 837–838. doi:10.1016/0190-9622(95)91846-9. PMID 7593791.
  7. Kieć-Swierczyńska M, Dudek B, Krecisz B, Swierczyńska-Machura D, Dudek W, Garnczarek A, Turczyn K (2006). "[The role of psychological factors and psychiatric disorders in skin diseases]" [The role of psychological factors and psychiatric disorders in skin diseases]. Medycyna Pracy (in Polish). 57 (6): 551–555. PMID 17533993.
  8. Vargas Laguna E, Peña Payero ML, Vargas Márquez A (December 2006). "[Influence of anxiety in diverse cutaneous diseases]" [Influence of anxiety in diverse cutaneous diseases]. Actas Dermo-Sifiliograficas (in Spanish). 97 (10): 637–643. doi:10.1016/s0001-7310(06)73484-6. PMID 17173825.
  9. Johansson O, Liang Y, Marcusson JA, Reimert CM (August 2000). "Eosinophil cationic protein- and eosinophil-derived neurotoxin/eosinophil protein X-immunoreactive eosinophils in prurigo nodularis". Archives of Dermatological Research. 292 (8): 371–378. doi:10.1007/s004030000142. PMID 10994770. S2CID 9095256.
  10. Gong JQ, Lin L, Lin T, Hao F, Zeng FQ, Bi ZG, et al. (October 2006). "Skin colonization by Staphylococcus aureus in patients with eczema and atopic dermatitis and relevant combined topical therapy: a double-blind multicentre randomized controlled trial". The British Journal of Dermatology. 155 (4): 680–687. doi:10.1111/j.1365-2133.2006.07410.x. PMID 16965415. S2CID 27948096.
  11. Lin YT, Wang CT, Chiang BL (December 2007). "Role of bacterial pathogens in atopic dermatitis". Clinical Reviews in Allergy & Immunology. 33 (3): 167–177. doi:10.1007/s12016-007-0044-5. PMID 18163223. S2CID 25203471.
  12. Guzik TJ, Bzowska M, Kasprowicz A, Czerniawska-Mysik G, Wójcik K, Szmyd D, et al. (April 2005). "Persistent skin colonization with Staphylococcus aureus in atopic dermatitis: relationship to clinical and immunological parameters". Clinical and Experimental Allergy. 35 (4): 448–455. doi:10.1111/j.1365-2222.2005.02210.x. PMID 15836752. S2CID 38030209.
  13. Horiuchi Y, Bae S, Katayama I (April 2006). "Uncontrollable prurigo nodularis effectively treated by roxithromycin and tranilast". Journal of Drugs in Dermatology. 5 (4): 363–365. PMID 16673805.
  14. Hyde JN, Montgomery FH: A practical treatise on disease of the skin for the use of students and practitioners. 1909; 174–175.
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