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]
Nodules are discrete, generally symmetric, hyperpigmented and firm. They are greater than 0.5cm in both width and depth (as opposed to papules which are less than 0.5cm).
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, etal. (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, etal. (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.
↑ Guzik TJ, Bzowska M, Kasprowicz A, Czerniawska-Mysik G, Wójcik K, Szmyd D, etal. (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.
Dermatitis is inflammation of the skin, typically characterized by itchiness, redness and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become thickened. The area of skin involved can vary from small to covering the entire body. Dermatitis is often called eczema, and the difference between those terms is not standardized.
Lichen simplex chronicus (LSC) is thick leathery skin with exaggerated skin markings caused by sudden itching and excessive rubbing and scratching. It generally results in small bumps, patches, scratch marks and scale. It typically affects the neck, scalp, upper eyelids, ears, palms, soles, ankles, wrists, genital areas and bottom. It often develops gradually and the scratching becomes a habit.
Itch is a sensation that causes a strong desire or reflex to scratch. Itches have resisted many attempts to be classified as any one type of sensory experience. Itches have many similarities to pain, and while both are unpleasant sensory experiences, their behavioral response patterns are different. Pain creates a withdrawal reflex, whereas itches leads to a scratch reflex.
Antipruritics, abirritants, or anti-itch drugs, are medications that inhibit the itching often associated with sunburns, allergic reactions, eczema, psoriasis, chickenpox, fungal infections, insect bites and stings like those from mosquitoes, fleas, and mites, and contact dermatitis and urticaria caused by plants such as poison ivy or stinging nettle. It can also be caused by chronic kidney disease and related conditions.
A boil, also called a furuncle, is a deep folliculitis, which is an infection of the hair follicle. It is most commonly caused by infection by the bacterium Staphylococcus aureus, resulting in a painful swollen area on the skin caused by an accumulation of pus and dead tissue. Boils are therefore basically pus-filled nodules. Individual boils clustered together are called carbuncles. Most human infections are caused by coagulase-positive S. aureus strains, notable for the bacteria's ability to produce coagulase, an enzyme that can clot blood. Almost any organ system can be infected by S. aureus.
Nummular dermatitis is one of the many forms of dermatitis. It is characterized by round or oval-shaped itchy lesions. The name comes from the Latin word "nummus," which means "coin."
Skin disorders are among the most common health problems in dogs, and have many causes. The condition of a dog's skin and coat is also an important indicator of its general health. Skin disorders of dogs vary from acute, self-limiting problems to chronic or long-lasting problems requiring life-time treatment. Skin disorders may be primary or secondary in nature, making diagnosis complicated.
Atopic dermatitis (AD), also known as atopic eczema, is a long-term type of inflammation of the skin (dermatitis). It results in itchy, red, swollen, and cracked skin. Clear fluid may come from the affected areas, which can thicken over time. AD may also simply be called eczema, a term that generally refers to a larger group of skin conditions.
Kimura's disease is a benign rare chronic inflammatory disorder. Its primary symptoms are subdermal lesions in the head or neck or painless unilateral inflammation of cervical lymph nodes.
Actinic prurigo is a rare sunlight-induced, pruritic, papular, or nodular skin eruption. Some medical experts use the term actinic prurigo to denote a rare photodermatosis that develops in childhood and is chronic and persistent; this rare photodermatosis, associated with the human leukocyte antigen HLA-DR4, is often called "Familial polymorphous light eruption of American Indians" or "Hereditary polymorphous light eruption of American Indians" but some experts consider it to be a variant of the syndrome known as polymorphous light eruption (PMLE). Some experts use the term actinic prurigo for Hutchinson's summer prurigo and several other photodermatoses that might, or might not, be distinct clinical entities.
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Uremic pruritus is caused by chronic kidney failure and is the most common internal systemic cause of itching.
Senile pruritus is one of the most common conditions in the elderly or people over 65 years of age with an emerging itch that may be accompanied with changes in temperature and textural characteristics. In the elderly, xerosis, is the most common cause for an itch due to the degradation of the skin barrier over time. However, the cause of senile pruritus is not clearly known. Diagnosis is based on an elimination criteria during a full body examination that can be done by either a dermatologist or non-dermatologist physician.
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