Pruritus The 5 Minute Pediatric Consult


	Pruritus

Mark L. Bagarazzi

The 5 Minute Pediatric Consult

Database
Differential Diagnosis
Approach to the Patient
Data Gathering
Physical Examination
Laboratory Aids
Emergency Care
Common Questions and Answers
Bibliography

DATABASE

DEFINITION

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

DIFFERENTIAL DIAGNOSIS

CONGENITAL/ANATOMICAL

Cholestasis secondary to biliary obstructio

INFECTIONS

Pinworm (enterobius vermicularis)
Swimmer itch: due to fresh water mammalian or avian schistosomes
Herpes viruses: primary Varicella infection or zoster, Herpes simplex
Borrelia burgdorferi: erythema chronicum migrans lesion of Lyme disease
Streptococcus pyogenes: sandpaper rash of scarlet fever
Tinea
Toxocara canis

TOXIC

Contact dermatitis
- Allergens
  - Plants (Rhus dermatitis—poison ivy)
  - Cosmetics
  - Dyes
  - Medications
- Irritants
  - Soaps
  - Detergents and other chemicals
  - Excrement
  - Wool
  - Fiberglass

ENVIRONMENTAL

Papular urticaria: bites of fleas, mosquitoes, etc.
Pediculosis (lice)
Mites: scabies (Sarcoptes scabei), chiggers (Enterobicula alfreddugesi), etc.
Subcutaneous foreign body
Phytophotodermatitis occurs when skin is exposed to sunlight after contact with an offending plant

DRUGS

Systemic use of medications such as aminophylline, aspirin, barbiturates, erythromycin, gold, griseofulvin, iodine contrast dyes, isoniazid, opiates, phenothiazines, vitamin A

ALLERGIC, INFLAMMATORY

Atopic dermatitis (eczema)
Psoriasis
Seborrheic dermatitis

MISCELLANEOUS

Non-specific urticaria
Pityriasis rosea
Asteatotic eczema—“winter itch”
Xerosis (dry skin)—from excess bathing with or without strong detergents or low humidity, idiopathic

APPROACH TO THE PATIENT

GENERAL GOALS

Determine severity and if the pruritus is isolated or due to an underlying systemic illness primarily by assessing the presence or absence of associated signs and symptoms, especially rash.

Phase 1: Assess the severity of the illness. Pruritus will rarely be an element of a medical emergency except in the cases of anaphylaxis or erythema multiforme-major (i.e., Stevens-Johnson syndrome).

Phase 2: 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. A thorough review of potential precipitating events and the duration of symptoms should be sought. Aside from the obvious need for a thorough examination of the skin, one should pay particular attention to manifestations of underlying diseases and physiologic states. Underlying states may range from hepatic or renal diseases to pregnancy or psychiatric disease. As always, one’s differential diagnosis should consider common causes first, 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 the majority of causes. Laboratory tests may be indicated in cases where the diagnosis is unclear.

HINTS FOR SCREENING PROBLEM

One may want to ask if this is a 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 the 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 (see table below).

Potential Contact Irritants

DATA GATHERING

HISTORY

Question: Has anything new or different been introduced to the child, especially anything that comes in contact with their skin?
Significance: See the table on the previous page for a list of potential contact irritants (see table Potential Contact Irritants).

Question: How often is the child bathed and with what?
Significance: Different soaps or detergents contain additives that may be more or less allergenic. Changes in soaps may be important as stated previously. Some soaps cause excessive dryness or possess heavy fragrances. Children who are bathed frequently with anything more than water may develop dry and irritated (pruritic) skin.

Question: Has the child been hiking or camping in a wooded area?
Significance: May be a clue to common skin irritation such as rhus dermatitis or poison ivy.

Question: Are there any underlying illness(es)?
Significance: There is a long list of illnesses that are associated with pruritus (see table Causes of Pruritus in Children).

Causes of Pruritus in Children

Question: Is anyone else itching?
Significance: This may identify a common source of a contact irritant. Also, it is common to see more than one family member with scabies or lice.

Question: Accompanied by rash or other signs and symptoms?
Significance: This general question is meant to elicit additional signs and symptoms of any of the systemic diseases listed in the table. For instance, arthritis and athralgias in SLE or JRA, jaundice in the cholestatic disorders.

Question: Has this ever happened before?
Significance: Atopic dermatitis will present as chronic or recurrent pruritic skin lesions.

PHYSICAL EXAMINATION

Finding: If rash is present, what is the appearance?
Significance:

Lesions appear in crops with varicella zoster, scabies, insect bites
Lesions are in groups of 3 or 4 with a central punctum in scabies
Papular lesions occur with insect bites, chiggers, pediculosis, contact dermatitis, pityriasis rosea, urticaria (wheal), and atopic dermatitis
Plaque and scale formation occur with psoriasis, xerosis, tinea, atopic dermatitis
Serpiginous lesions occur with cutaneous larva migrans and myiasis (or maggots)
Vesicular lesions occur with varicella (generalized), scabies, poison ivy (linear), and atopic dermatitis
Dry skin (xerosis) occurs with atopic dermatitis
Christmas tree pattern occurs with pityriasis rosea

Finding: What is the location of the itch and/or rash?
Significance:

Generalized distribution occurs with varicella
Anus: consider pinworms
Back: consider pityriasis rosea
Axillae and/or diaper area: consider seborrheic dermatitis and scabies
Dorsal foot: consider shoe dermatitis from rubber or tanning agents
Exposed surfaces: consider swimmer itch and poison ivy
Finger, ear lobe, wrist, or necklace distribution: consider irritant contact dermatitis (e.g., nickel)
Interdigital areas: consider tinea pedis, scabies
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

Finding: Abnormal affect or mood?
Significance: If after an exhaustive search there appears to be no physiological basis for the itch, one must consider whether the complaint is psychosomatic or due to neurotic excoriation especially in cases of abnormal affect or mood.

LABORATORY AIDS

Test: Wood light examination, KOH preparation.
Significance: Screen for tinea infections.

Test: Skin scraping in oil under cover slip.
Significance: Verify presence of mites in scabies.

Test: Perianal adhesive tape slide (preferably early morning).
Significance: Verify pinworm.

Test: Serum for hepatic and renal function.
Significance: Screen for underlying disease.

Test: Urine b-HCG
Significance: Investigate presence of cholestasis associated with pregnancy.

Indications for Referral

Identification of an underlying state, such as pregnancy, or hepatic, renal, or psychiatric disease.
Some severe cases of atopic dermatitis or psoriasis (may require dermatological referral).
Identification of pubic pediculosis (may require investigation into abuse).

EMERGENCY CARE

Pruritus due to anaphylaxis will require initial management of airway, breathing, and circulation (ABCs) followed by sympathomimetics (such as epinephrine), antihistamines (such as diphenhydramine), corticosteroids, and possibly fluid resuscitation.
Pruritus associated with Stevens-Johnson syndrome will require the equivalent of burn management with the need for fluid resuscitation.

Clinical Pearls

Pruritis that is worse at night points to either scabies or pinworm.
If the child was recently swimming in fresh water, one should consider swimmer itch, caused by fresh water mammalian or avian schistosomes.

COMMON QUESTIONS AND ANSWERS

Q: Is there any symptomatic treatment for pruritus other than antihistamines?
A: There have been a number of anecdotal references to other agents being effective for pruritus including: ursodeoxycholic acid in liver disease, opiate antagonists (such as naloxone and naltrexone), propofol at subhypnotic doses, cholestyramine, rifampin, and serotonin antagonists.

Q: Does the time course of a pruritic rash give any clue in identifying the offending agent?
A: Yes, certain plants will cause an immediate welt on the skin but the urticaria will be short-lived (immediate contact dermatitis). Skin that is traumatized mechanically (e.g., cactus spine) or chemically (e.g., capsaicin in hot peppers) produce more persistent skin reactions. Poison ivy or Rhus dermatitis is a type of allergic contact dermatitis that only occurs in previously sensitized persons. It is due to a cellular immune response and may last several weeks.

BIBLIOGRAPHY

Gilchrist BA. Pruritus: pathogenesis, therapy and significance in systemic disease states. Arch Intern Med 1982;142:101.

Greaves MW. Anti-itch treatments: do they work? Skin Pharmacol 1997;10:225–229.

Greaves MW, Wall PD. Pathophysiology of itching. Lancet 1996;348:938–40.

Hagermark O, Wahlgren CF. Treatment of itch. Semin Dermatol 1995;14:320–325.

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