Prurigo nodularis (PN), also known as nodular prurigo, is a
skin disorder characterized by pruritic (
itchy), nodular lesions, which commonly appear on the trunk, arms and legs.[1] Patients often present with multiple
excoriated nodules caused by chronic scratching. Although the exact cause of PN is unknown, PN is associated with other dermatologic conditions such as untreated or severe atopic dermatitis and systemic causes of pruritus including liver disease and end stage kidney disease.[2] The goal of treatment in PN is to decrease the itch sensation. PN is also known as Hyde prurigo nodularis, or Picker's nodules.[3]
Signs and symptoms
Nodules are discrete, generally symmetric, hyperpigmented 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).
The nodules of PN can appear on any part of the body, but generally are found in areas where patients are able to reach to scratch. Patients can exhibit a 'butterfly sign' in which nodules are absent in the mid upper back.[1][4]
Nodular lesions are often excoriated from persistent scratching.
The nodules in PN are extremely itchy, this sensation can have an impact on patients perceived quality of life[5]
The exact cause of prurigo nodularis is unknown, however, it is thought to be induced by other dermatologic conditions such as severe atopic dermatitis,
Becker's nevus,[6] and
linear IgA disease[7]. PN is also associated with systemic causes of pruritus such as liver disease,[8] cholestasis, thyroid disease, polycythemia vera, uremia, Hodgkins lymphoma,
HIV and kidney failure diseases.[9][10] 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.[11][12]
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.[citation needed]
Diagnosis is based on visual examination and the presence of itching for greater than 6 weeks duration.
[13]A skin biopsy is often performed to exclude other diseases. Lesion biopsies usually show light inflammation, sometimes with increased numbers of
eosinophils.[14] A culture of at least one lesion will rule out staphylococcus infection, which has been significantly linked to atopic dermatitis.[15][16][17]
Treatment
Prurigo nodularis is very hard to treat, but current therapies include steroids,
dupilumab, vitamins,
cryosurgery,
thalidomide and
UVB light[citation needed]. 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.[18]
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.[citation needed]
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.[19]
^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.
PMID17184268.
S2CID32658695.
^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.
PMID16882196.
S2CID28166468.
^Hiramanek N (July 2004). "Itch: a symptom of occult disease". Australian Family Physician. 33 (7): 495–499.
PMID15301165.
^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.
PMID7593791.
^Kieć-Swierczyńska M, Dudek B, Krecisz B, Swierczyńska-Machura D, Dudek W, Garnczarek A, et al. (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.
PMID17533993.
^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.
PMID17173825.[permanent dead link]
^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.
PMID10994770.
S2CID9095256.
^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.
PMID16965415.
S2CID27948096.
^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.
PMID18163223.
S2CID25203471.
^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.
PMID15836752.
S2CID38030209.
^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.
PMID16673805.
^Hyde JN, Montgomery FH: A practical treatise on disease of the skin for the use of students and practitioners. 1909; 174–175.