Pruritus

Mark R. Bagarazzi, MD

Pruritus - BASICS

Pruritus - description

Itching, an unpleasant cutaneous sensation that provokes the desire to rub or scratch the skin to obtain relief

Pruritus - DIAGNOSIS

General goals:

• Determine severity and if pruritus is isolated or owing to an underlying systemic illness, primarily by assessing the presence or absence of associated signs and symptoms, especially rash.
• Phase 1: Assess severity of illness. Pruritus rarely constitutes a medical emergency except in cases of anaphylaxis or erythema multiforme major (i.e., Stevens-Johnson syndrome).
• Phase 2: A thorough review of potential precipitating events and the duration of symptoms will help determine if the itch is isolated or if there are any associated signs or symptoms. Pruritus is most frequently associated with rash. Pruritus with or without rash may be a manifestation of systemic illness. Underlying states may range from hepatic or renal diseases to pregnancy or psychiatric disease. As always, differential diagnosis should consider common causes 1st, then entertain less common and even rare causes.
• Phase 3: A thorough history and examination should narrow the differential diagnosis considerably, enabling the clinician to determine the underlying cause of the complaint in most cases. Laboratory tests may be indicated in cases where the diagnosis remains unclear.

Pruritus - signs & symptoms

Pruritus - history

• New or recurrent problem?
  • If it is new, one should ask if there is anything new in the child’s life that may be associated with the onset of pruritus (with or without rash). This is often the most revealing question as one may find that the child recently came in contact with a new item, which is known to be a contact irritant.
• How severe is the pruritus? On a scale of 1–10? Compared with a mosquito bite? Is it severe enough to interfere with the daily routine of the child (e.g., wakes the child from sleep)?
  • Answers will provide some measure of the true severity of the problem. Waking from sleep may suggest a more severe form resulting from systemic disease.
• Introduction of anything new or different, especially anything that comes in contact with the child’s skin:
  • Frequency of baths and types of products used to bathe the child
  • Different soaps or detergents contain additives that may be allergenic. Changes in soaps may be important. Some soaps cause excessive dryness or contain heavy fragrances. Children who are bathed frequently with anything more than water may develop dry and irritated (pruritic) skin.
• If child has been hiking or camping in a wooded area, may be a clue to common skin irritation (rhus dermatitis)
• Any underlying illness(es) or associated symptoms:
  • Pruritus associated with night sweats and fever may point to hematopoietic malignancy. Many illnesses are associated with pruritus (see “Causes of Pruritus in Children”).
• Complaints about itching from anyone who has frequent contact with the child:
  • May identify a common source of a contact irritant. For example, one will often see multiple family members affected by scabies or lice.
• Is the pruritus accompanied by rash or other signs and symptoms?
  • This general question is meant to elicit additional signs and symptoms of any of the systemic diseases listed in “Causes of Pruritus in Children.” For instance, arthritis and arthralgias are seen in systemic lupus erythematosus and juvenile rheumatoid arthritis, and jaundice in the cholestatic disorders.
• If itching has happened before, atopic dermatitis will present as chronic or recurrent pruritic skin lesions.

Pruritus - physical exam

• If rash is present, appearance of rash:
  • Lesions appear in crops with varicella zoster, scabies, and insect bites.
  • Lesions are in groups of 3 or 4 with a central punctum in scabies.
  • Papular lesions result from insect bites, chiggers, pediculosis, contact dermatitis, pityriasis rosea, urticaria (wheal), and atopic dermatitis.
  • Lichenification occurs with psoriasis, xerosis, tinea, and atopic dermatitis.
  • Serpiginous lesions occur with cutaneous larva migrans and myiasis (or maggots).
  • Vesicular lesions occur in varicella (generalized), scabies, poison ivy (linear), and atopic dermatitis.
  • Dry skin (xerosis) occurs in atopic dermatitis.
  • Christmas tree pattern occurs in pityriasis rosea.
• Location of the itch and/or rash:
  • Generalized distribution: Consider varicella.
  • Anus: Consider pinworms.
  • Back: Consider pityriasis rosea.
  • Axillae and/or genital/diaper area: Consider seborrheic dermatitis and scabies.
  • Dorsal foot: Consider shoe dermatitis from rubber or tanning agents.
  • Exposed surfaces: Consider schistosomal dermatitis and poison ivy.
  • Finger, ear lobe, wrist, or necklace distribution: Consider irritant contact dermatitis (e.g., nickel).
  • Nipples: Consider scabies (burrows).
  • Interdigital areas and ulnar borders: Consider tinea pedis or scabies (burrows).
  • Palms and/or soles: Consider biliary cirrhosis.
  • Plantar foot: Consider cutaneous larva migrans.
  • Scalp: Consider pediculosis (nits found cemented to hair shaft) and tinea capitis.
• Abnormal affect or mood: If after an exhaustive search there appears to be no physiologic basis for the itch, one must consider whether the complaint is a conversion disorder or owing to neurotic excoriation, especially in cases of abnormal affect or mood.
• Enlargement of liver, spleen, or lymph nodes: Pruritus may be the initial manifestation of lymphoma.

Pruritus - tests

Pruritus - lab

• CBC with differential: Presence of eosinophilia suggests atopy or parasitic infections.
• Wood lamp examination, potassium hydroxide preparation: Screen for tinea infections.
• Serum for hepatic and renal function: Screen for underlying disease.
• Urinalysis for β-human chorionic gonadotropin: Investigate presence of cholestasis associated with pregnancy.

Pruritus - diag proced-surgery

• Skin biopsy: Usually not of value because histologic changes may result from the scratching itself
• Skin scraping in oil under cover slip: Presence of mites in scabies
• Perianal adhesive tape slide (preferably early morning): Verify pinworms.

Pruritus - differencial diagnosis

• Congenital/Anatomic:
  • Cholestasis secondary to biliary obstruction (e.g., Alagille syndrome)
  • Infectious:
  • Pinworms (Enterobius vermicularis): Pruritus that is worse at night is seen with scabies or pinworm.
  • Swimmer’s itch (owing to fresh water mammalian or avian schistosomes): If the child was recently swimming in fresh water, consider swimmer’s itch, caused by fresh water mammalian or avian schistosomes.
  • Seabather’s eruption (affects swimmers and divers in marine waters off Florida, in the Gulf of Mexico, and the Caribbean; attributed to various organisms but more recently to the larvae of the thimble jellyfish, Linuche unguiculata)
  • Herpes viruses: Primary varicella infection or herpes zoster; herpes simplex
  • Borrelia burgdorferi: Erythema chronicum migrans lesion associated with Lyme disease
  • Streptococcus pyogenes: Sandpaper rash of scarlet fever
  • Tinea corporis
  • Toxocariasis canis
• Toxic:
  • Contact dermatitis (see “Potential Contact Irritants”):

    Medications (see below) Allergens	Plants (e.g., rhus dermatitis—poison ivy/oak, cacti)
    Cosmetics	Foods
    Chemicals (e.g., soaps and detergents)	Capsaicin in hot peppers*
    Dyes (for hair, e.g.)	Animals
    Jewelry (nickel)	Clothing (e.g., wool)
    Fiberglass	Shoes
    Excrement	Diapers

    *Acts as an irritant on 1st contact but may actually decrease pruritus if applied repeatedly over weeks

• Environmental:
  • Papular urticaria: Bites of fleas, mosquitoes
  • Pediculosis (lice)
  • Mites: Scabies (Sarcoptes scabiei), chiggers (Trombicula alfreddugesi)
  • Subcutaneous foreign body
  • Phytophotodermatitis occurs when skin is exposed to sunlight after contact with an offending plant.
• Drugs:
  • Systemic use of medications (e.g., aminophylline, aspirin, barbiturates, chloroquine, erythromycin, gold, griseofulvin, iodine contrast dyes, isoniazid, opiates, phenothiazines, vitamin A)
• Allergic, inflammatory:
  • Atopic dermatitis (eczema)
  • Psoriasis
  • Seborrheic dermatitis
• Miscellaneous:
  • Burns
  • Nonspecific urticaria
  • Pityriasis rosea
  • Asteatotic eczema (“winter itch”)
  • Xerosis (dry skin) owing to excess bathing with or without strong detergents or in low humidity; idiopathic

Pruritus - TREATMENT

Pruritus - initial stabilization

Pruritus owing to anaphylaxis will require initial management of airway, breathing, and circulation (ABCs) followed by sympathomimetics (e.g., epinephrine), antihistamines (e.g., diphenhydramine), corticosteroids, and possibly fluid resuscitation.

Pruritus - FOLLOW UP

Pruritus - disposition

Pruritus - issues for referral

• Identification of an underlying disorder or state
• Some severe cases of atopic dermatitis or psoriasis may require dermatologic referral.
• Identification of pubic pediculosis may require investigation for child sexual abuse.

Pruritus - bibliography

1. Charlesworth EN, Beltrani VS. Pruritic dermatoses: Overview of etiology and therapy. Am J Med. 2002;113(suppl 9A):25S–33S.
2. Millikan LE. Pruritus: Unapproved treatments or indications. Clin Dermatol. 2000;18:149–152.
3. Paus, R, Schmelz M, Biro T, et al. Frontiers in pruritus research: Scratching the brain for more effective itch therapy. J Clin Invest. 2006;116:1174–1186.
4. Wahlgren CF. Itch and atopic dermatitis: An overview. J Dermatol. 1999;26:770–779.

Pruritus - CODES

Pruritus - icd9

698 Pruritus and related conditions

Pruritus - FAQ

• Q: Does the time course of a pruritic rash give any clue in identifying the offending agent?
• A: Yes, certain plants cause an immediate welt on the skin, but the urticaria is short lived (immediate contact dermatitis). Skin that is traumatized mechanically (e.g., cactus spine) or chemically (e.g., capsaicin as found in hot peppers) produces more persistent skin reactions. Poison ivy, or rhus dermatitis, is a type of allergic contact dermatitis that only occurs in those previously sensitized. It is owing to a cellular immune response and may persist several weeks.
• Q: Are some antihistamines better than others for pruritus?
• A: Possibly; evidence is conflicting, but several studies have shown that older systemic antihistamines that cause greater somnolence are actually more effective at alleviating pruritus than newer, longer-acting antihistamines (e.g. astemizole, loratadine, terfenadine, cetirizine).
• Q: Is there any symptomatic treatment for pruritus other than antihistamines?
• A: Yes, systemic and topical corticosteroids and topical pramoxine and doxepin have been shown to be effective in placebo-controlled trials. Some anecdotal references to other agents that are effective for pruritus include ursodeoxycholic acid in liver disease, opiate antagonists (e.g., naloxone and naltrexone), propofol at subhypnotic doses, cholestyramine, rifampin, and serotonin antagonists (e.g., ondansetron).
• Q: Should tacrolimus and pimecrolimus be used for atopic dermatitis?
• A: Only as second-line therapy for the short-term and noncontinuous chronic treatment of mild to moderate atopic dermatitis in non-immunocompromised children 2 years of age and older who have failed to respond adequately to other topical prescription treatments, or when those treatments are not advisable. These drugs carry a “Black Box” warning about a possible risk of cancer. The Medication Guide is to be distributed with each prescription to help ensure that patients using these prescription medicines are aware of this concern.
• Q: Do topical antihistamines alleviate pruritus?
• A: Not usually, except for widespread pruritus seen with insect bites and urticaria. Use of topical antihistamines for pruritus or rash that is widespread should be discouraged, because toxicity may result from systemic absorption.
• Q: Does scratching make the pruritus better or worse?
• A: Worse; scratching leads to the release of the mediators of inflammation including histamine that, in turn, leads to more pruritus thus creating a vicious cycle.
• Q: Are there any useful adjuncts to reduce pruritus?
• A: Yes, keeping skin moist with moisturizers and avoiding dry environments. Avoid overwashing, especially with hot water and/or alkaline soaps.

Book Source Details

• Book Title: The 5-Minute Pediatric Consult
• Author(s): M. William Schwartz MD; et al.
• Year of Publication: 2008
• Copyright Details: The 5-Minute Pediatric Consult, Copyright © 2008 Lippincott Williams & Wilkins.

Other Book Chapters Related to Aquagenic pruritus

Read excerpts from these other book chapters related to Aquagenic pruritus:

Copyright Details: The 5-Minute Pediatric Consult, Copyright © 2008 Williams & Wilkins.

More About Causes of Aquagenic pruritus

• Back to symptom: Aquagenic pruritus: Introduction (review 3 causes)
• Next Book Extract About Aquagenic pruritus: Videos relating to Aquagenic pruritus
• All Book Extracts: All Online Book Extracts for Aquagenic pruritus

More About This Book: Title: The 5-Minute Pediatric Consult Authors: M. William Schwartz MD; et al. Publisher: Lippincott Williams & Wilkins Copyright: 2008 ISBN: 0-7817-7577-9

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