Upload
giantagnan
View
218
Download
0
Embed Size (px)
Citation preview
7/28/2019 itch in medicine
1/10
About Us1.myCME Login2.
Contact Us3.FAQ4.
Monthly CME eNewsletter5.Text Size:6.
A7.A8.A9.
All documents
Pagina 1 di 10Pruritus
12/14/2011http://www.clevelandclinicmeded.com/medicalpubs/diseasemanagement/dermatology/pru...
7/28/2019 itch in medicine
2/10
SECTION INDEXAllergy & ImmunologyCardiologyDermatologyEndocrinologyGastroenterologyHematology & OncologyHepatologyInfectious Disease
NephrologyNeurologyPreventive MedicinePsychiatry & PsychologyPulmonary DiseaseRheumatologyWomen's Health
DISEASE MANAGEMENT PROJECT MAINChapter IndexEditorial BoardEditorial Policy
Published:August 1, 2010
Related CME casesDisease Management Project Clinical Decisions
Pruritus
James S. Taylor
Matthew J. Zirwas
Apra Sood
0
Definition and etiology
Pruritus or itch is defined as an unpleasant sensation of the skin that provokes the urge to scratch. It is a characteristic feature
of many skin diseases and an unusual sign of some systemic diseases.1, 2 Pruritus may be localized or generalized and can
Pagina 2 di 10Pruritus
12/14/2011http://www.clevelandclinicmeded.com/medicalpubs/diseasemanagement/dermatology/pru...
7/28/2019 itch in medicine
3/10
occur as an acute or chronic condition. Itching lasting more than 6 weeks is termed chronic pruritus.2 Itching can be intractable
and incapacitating, as well as a diagnostic and therapeutic challenge.
Back to Top
Prevalence, risk factors, and natural history
Prevalence estimates, risk factors, and natural history exist for only a few specific disorders associated with itching and arementioned in the discussion of those conditions.
Back to Top
Pathophysiology
Peripheral MechanismsPhysical Stimuli and Neural Pathways
Itch can be produced by mechanical (gentle touch, pressure, vibration, and wool), thermal and electrical stimuli such as
transcutaneous or direct nerve stimulation. The sensation is received by free nerve endings in the skin and transmitted via
unmyelinated C fibers and myelinated A fibers to the central spinothalamic tracts.1, 2
Microneurography studies havedemonstrated that itch and pain are transmitted by separate neural pathways.3, 4
Chemical Mediators
Histamine is one of the most important mediators of itch, although other chemical substances have also been implicated.3
Some, such as neuropeptides, act by releasing histamine from mast cells, and itching caused by them responds to
antihistamines. Others act independently; therefore antihistamines are not effective in some forms of pruritus. Opioids have a
central pruritic action and also act peripherally by augmenting histamine itch.
Central Mechanism
Patients with tumors and lesions of the central nervous system have been reported to have intractable pruritus.
1, 5-7
Administration of opioids in epidural anesthesia can also lead to pruritus.
Etiology
Itching is associated with dermatologic and systemic causes, and it is important to determine whether there is an associated
skin eruption. A characteristic rash usually establishes the diagnosis of a primary dermatologic disorder. Several skin diseases
are associated with pruritus; some are listed in Box 1. Itching is an important component of some disorders (atopic eczema,
dermatitis herpetiformis, lichen simplex chronicus, and nodular prurigo) and these conditions are rarely diagnosed in its
absence. In conditions such as mild urticaria or aquagenic pruritus, the levels of histamine are sufficient for a sensory but not a
vascular response, and there may be no skin findings. Bullous pemphigoid can manifest with a prebullous pruritic phase for
several months before the characteristic blisters appear.8An invisible form of mycosis fungoides can occur as pruritus without
a rash and is diagnosed on biopsy.9
Box 1: Select Dermatologic Disorders Associated with Chronic Pruritus*
Autoimmune
Dermatitis herpetiformis
Dermatomyositis
Pemphigoid
Sjgren's syndrome
Pagina 3 di 10Pruritus
12/14/2011http://www.clevelandclinicmeded.com/medicalpubs/diseasemanagement/dermatology/pru...
7/28/2019 itch in medicine
4/10
Genetic
Darier's disease
Hailey-Hailey disease
Ichthyoses
Sjgren-Larsson syndrome
Infections and Infestations
Arthropod reactions
Dermatophytosis
Folliculitis
Impetigo and other bacterial infections
Insect bites
Pediculosis
Scabies
Viral
Inflammatory
Asteatosis (dry skin), including aging and senile pruritus
Atopic eczema
Contact dermatitis (irritant, allergic)Drug reactions
Invisible dermatoses
Lichen planus
Lichen simplex chronicus
Mastocytosis (urticaria pigmentosa)
Miliaria
Psoriasis
Scars
Urticaria
Neoplastic
Cutaneous T-cell lymphoma or mycosis fungoides (especially Szary syndrome)
Cutaneous B-cell lymphoma
Leukemia cutis
Pregnancy
Pemphigoid gestationis
Polymorphic eruption of pregnancy
Prurigo gestationis
*Generalized or localized depending on extent of disease
Adapted from Pujol RM, Gallardo F, Llistosella E, et al: Invisible mycosis fungoides: A diagnostic challenge. J Am Acad Dermatol 2002;47:S167-S171; and StnderS, Weisshaar E, Mettang T, et al: Clinical Classification of itch: A position paper of the International Forum for the Study of Itch. Acta Derm Venereol 2007:87 291-294.
It is important to establish if pruritus preceded the appearance of a skin eruption. Severe itching leads to scratching that
causes secondary skin changes of excoriation, lichenification, dryness, eczematization, and infection. Excessive bathing and
contact allergy to topical therapies can lead to dermatitis. These findings should not be interpreted as the primary skin
disorder.
Select systemic conditions associated with itching are listed in Box 2. Several are potentially serious, and it can be dangerous
to label a case of generalized pruritus nonspecific eczema until these conditions are excluded. Pruritus of systemic disease is
usually generalized, it may be the only manifesting symptom, and a specific rash is not present. Neurologic and psychiatric
conditions associated with chronic pruritus are included in Box 2.
Pagina 4 di 10Pruritus
12/14/2011http://www.clevelandclinicmeded.com/medicalpubs/diseasemanagement/dermatology/pru...
7/28/2019 itch in medicine
5/10
Box 2: Select Systemic Causes of Chronic Pruritus
Endocrine and Metabolic Diseases
Chronic renal failure
Diabetes mellitus (questionable; may be localized to scalp)
Hyperthyroidism
Hypothyroidism
Liver disease (with or without cholestasis)
Malabsorption
Perimenopausal pruritus
Infectious Diseases
Helminthosis
HIV infection
Parasitosis
Neoplastic and hematological
Hodgkin's disease
Iron deficiency
LeukemiaNon-Hodgkin's lymphoma
Multiple myeloma
Plasmacytoma
Polycythemia rubra vera
Visceral Neoplasms
Carcinoid syndrome
Solid tumors of the cervix, prostate, or colon
Pregnancy
Pruritus gravidarum (with or without cholestasis)
Drugs
Allopurinol
Amiodarone
Angiotensin-converting enzyme inhibitors
Estrogen
Hydrochlorothiazide
Hydroxyethyl cellulose
Opioids
Simvastatin
Other
Neurologic diseaseAbscess1.
Infarcts2.
Multiple sclerosis3.
Nostalgia paresthetica4.
Tumors5.
Psychiatric diseaseAnxiety disorders1.
Depression2.
Obsessive-compulsive disorder3.
Pagina 5 di 10Pruritus
12/14/2011http://www.clevelandclinicmeded.com/medicalpubs/diseasemanagement/dermatology/pru...
7/28/2019 itch in medicine
6/10
Adapted from Pujol RM, Gallardo F, Llistosella E, et al: Invisible mycosis fungoides: A diagnostic challenge. J Am Acad Dermatol 2002;47:S167-S171; and StnderS, Weisshaar E, Mettang T, et al: Clinical Classification of itch: A position paper of the International Forum for the Study of Itch. Acta Derm Venereol 2007:87 291-294.
Back to Top
Diagnosis
History
A detailed history is the single most important step toward diagnosing the cause of itching. This should include information on
the onset, extent (generalized vs. localized), severity, type of itch, aggravating and alleviating factors, diurnal and seasonal
variations, bathing, occupation, hobbies, medication history and allergies, and past medical and surgical history. Inquire about
personal or family history of atopy (childhood eczema, allergic rhinitis, asthma), household and other contacts, pets, travel
history, sexual history, and history of intravenous drug use (human immunodeficiency virus [HIV] or hepatitis C infection). If the
patient has recently undergone surgery, ask if hydroxyethyl cellulose was used as a plasma expander, because this substance
can be associated with intense generalized pruritus lasting for up to one year.
Review of SystemsA detailed history is important in chronic pruritus of unknown origin, including general health (fever, chills, weight loss); skin
(pigmentation, sweating, asteatosis, plethora, and jaundice); hair (growth, texture, loss); nails (Beau's lines, onycholysis, color
changes); eyes (exophthalmos, color changes); and endocrine, hematopoietic, gastrointestinal, genitourinary, neurologic, and
mental status.5-7, 10
Physical Examination
The skin should be examined for evidence of any recognizable disorder. Scratching (causing excoriations) or rubbing
(producing papules, nodules, and lichenified plaques) can lead to secondary changes that should not be interpreted as a
primary skin disorder but can mimic one. Examination of the upper midback can help in this distinction, because it is relatively
inaccessible and unavailable for scratching.
Look for evidence of parasitic infestation, especially scabies and lice. Examination of the skin, hair, and genitalia with
surveillance scrapings can identify either disorder. Examination of clothing seams can identify body lice in the unkempt
(vagabond's disease).
A complete physical examination to look for other cutaneous signs mentioned in the Review of Systems section is essential.
Pelvic and rectal examination as well as examination of the lymph nodes, liver, and spleen is important.5-7, 10
Investigations
In some cases, the diagnosis is apparent from the history, physical examination, or bedside studies (such as a scabies
preparation). When the diagnosis is not apparent, laboratory studies may be indicated.
In general, the laboratory investigation should be directed by the findings of the history and physical examination. In a patient
with no pertinent findings, a reasonable initial screen consists of complete blood count, complete metabolic panel, hepatitis C
antibodies, TSH, and chest x-ray. Based on the initial results and the course of the pruritus, further testing may be indicated
(Box 3).
Box 3: Laboratory Investigations for Generalized Pruritus
Initial Screening Studies
Complete blood count with differential
Blood urea nitrogen, creatinine
Pagina 6 di 10Pruritus
12/14/2011http://www.clevelandclinicmeded.com/medicalpubs/diseasemanagement/dermatology/pru...
7/28/2019 itch in medicine
7/10
Aspartate transaminase, alanine aminotransferase, alkaline phosphatase, bilibrubin
Hepatitis C antibodies
Thyroid-stimulating hormone
Chest x-ray
Other Studies*
Allergy panelHistamine1.
Mast cell metabolites2.
Serotonin3.
Total IgE4.
Urine 5-HIAA5.
Antinuclear antibody
Antimitochondrial antibodies
Antitissue transglutaminase antibodies
Calcium and phosphate levels
Erythrocyte sedimentation rate
Fasting glucose, hemoglobin A1C
HIV screen
Pancomputed tomography scan
Prick testing, patch testing
Serum and urine immunofixation
Serum and urine protein electrophoresis
Serum iron and ferritin
Skin biopsy with immunofluorescenceStool for occult blood, ova, and parasites
Upper and/or lower endoscopy
*To be considered based on history and physical examination, results of initial laboratory screening, and pruritus.
5-HIAA, 5-hydroxyindoleacetic acid; IgE, immunoglobulin E.Adapted from Kantor GR, Bernhard J: Investigation of the pruritic patient in daily practice. Semin Dermatol. 1995;14:290-296.
Histopathologic examination of the skin lesions may be required. In pruritus without a rash, a biopsy specimen for direct
immunofluorescence from normal-appearing skin might show immune deposits in early cases of pemphigoid or findings
diagnostic of mycosis fungoides in routine histopathology.
Patients with chronic idiopathic pruritus should be followed with periodic re-evaluation if the symptoms persist, because an
underlying disorder can manifest later.5-7, 10
Back to Top
Treatment
General Concepts and Topical and Systemic Treatments
Identifying and treating the underlying cause is the most effective therapy for pruritus. Symptomatic treatment should be
prescribed while the primary condition is being treated. Cool compresses and cool baths might help relieve the itch; a cool
environment in the home and workplace also helps. Cooling lotions with calamine, pramoxine, or menthol and camphor are
helpful (Box 4).
Box 4: Outline for Selected Treatments for Pruritus
Topical
Anesthetics
Antipruritics
Cooling agents
Corticosteroids
Emollients
Pagina 7 di 10Pruritus
12/14/2011http://www.clevelandclinicmeded.com/medicalpubs/diseasemanagement/dermatology/pru...
7/28/2019 itch in medicine
8/10
Systemic
Antihistamines
Corticosteroids
Opioid-receptor antagonist
Phototherapy
Ultraviolet B, broad band or narrow band
Ultraviolet A1
Miscellaneous
Acupuncture
Capsaicin
Transcutaneous electrical stimulation
Adapted from Hagermark O, Wahlgren C: Treatment of itch. Semin Dermatol 1995;14:320-325.
Pruritus due to dry skin, especially in the elderly, responds to generous amounts of emollients such as petrolatum and whiteparaffin, as well as correcting the temperature and humidity. Patients should avoid frequent and hot baths and excessive use
of soap, which further dries the skin. Topical corticosteroids should not be prescribed indiscriminately but should be used only
if there are signs of cutaneous inflammation. Topical tacrolimus may be prescribed for limited use in patients with atopic
dermatitis. Topical capsaicin may be useful in chronic localized pruritus such as notalgia paresthetica.
H1-receptor antihistamines are the drugs of choice for urticaria. The newer nonsedating antihistamines are less effective in
atopic dermatitis; the older sedating antihistamines might work better. Tricyclic antidepressants such as doxepin have
antihistamine activity in addition to central effects and are useful in chronic, severe pruritus. Gabapentin, buspirone, and
selective serotonin reuptake inhibitors (SSRIs) may be considered in select patients. Ultraviolet (UV) B phototherapy is very
effective in uremic pruritus and may be helpful in patients with prurigo nodularis, atopic dermatitis, HIV infection, and
aquagenic pruritus. Opioid-receptor antagonists, such as naloxone, have occasionally been used for intractable pruritus of
renal and cholestatic diseases. Other measures that have been tried for chronic pruritus are acupuncture and transcutaneouselectrical nerve stimulation (TENS) (see Box 4).
Aggressive treatment of the eczema may be the only way to control the pruritus in patients with atopic dermatitis. Limited use
of systemic corticosteroids as well as other systemic immunosuppressives may be needed to treat the eczema.1, 10
Treatment of Specific DisordersChronic Renal Disease
Other than general treatments as mentioned earlier, mild disease might respond to UVB phototherapy and erythropoietin.
Second-line treatments include oral activated charcoal, cholestyramine, and the opioid antagonist naltrexone. Third-line
therapies include thalidomide and parathyroidectomy.1,10
Dialysis can provide some relief but rarely improves itching significantly. Parathyroid hormone levels have been found to be
increased and have been implicated as a cause. These patients experience relief of pruritus after parathyroidectomy.6 Renal
transplantation is the definitive treatment.1,10
Cholestatic Disease
Ion-exchange resins, such as cholestyramine, probably act by lowering levels of bile salts and other pruritogens. Altered
central opioidergic neurotransmission is believed to be a contributing factor, 12 and opioid antagonists such as naloxone and
naltrexone have been found useful.13 Second-line therapies include rifampicin, which has been shown to reduce pruritus in
Pagina 8 di 10Pruritus
12/14/2011http://www.clevelandclinicmeded.com/medicalpubs/diseasemanagement/dermatology/pru...
7/28/2019 itch in medicine
9/10
patients with primary biliary cirrhosis, 14 ursodeoxycholic acid, SSRIs, and S-adenosylmethionine. Third-line treatment includes
UVB phototherapy, extracorporeal albumin dialysis, plasmapheresis, and dronabinol, a cannabinoid.1, 10
Polycythemia Rubra Vera
Antihistamines are usually ineffective, but psoralen plus ultraviolet A (PUVA) phototherapy has been helpful in some patients.
Aspirin has been reported effective, and a trial showed SSRIs to be effective.1, 10
Back to Top
Summary
Pruritus or itch is a characteristic feature of many skin diseases and an unusual sign of some systemic diseases.
The presence of skin changes does not exclude the possibility of an underlying systemic cause of the pruritus.
The absence of a rash does not automatically mean that the underlying cause of the itching is a systemic disease.
Dermatologic and internal medicine evaluations, including laboratory tests, skin biopsy, and radiographic studies as
dictated by history and physical findings, should be considered for patients with generalized pruritus lasting longer than
6 weeks.
Identifying and treating the underlying cause are the most effective therapies for pruritus.
Back to Top
References
Ward JR, Bernhard JD. Pruritus. In: Lebwohl M, Heymann WR, Berth-Jones J, Coulson I (eds): Treatment of Skin
Disease. 2nd ed. St Louis: Mosby Elsevier, 2006, pp 533-537.
1.
Stnder S, Weisshaar E, Mettang T, et al: Clinical Classification of itch: A position paper of the International Forum for
the Study of Itch. Acta Derm Venereol. 2007, 87: 291-294.
2.
Stnder S, Steinhoff M, Schmelz M, et al: Neurophysiology of pruritus: Cutaneous elicitation of itch. Arch Dermatol.
2003, 139: 1463-1470.
3.
Greaves M. Mediators of pruritus. In: Bolognia JL, Jorizzo JL, Rapini RP (eds): Dermatology. St Louis: Mosby, 2003,
pp 85-94.
4.
Zirwas MJ, Seraly MP. Pruritus of unknown origin: A retrospective study. J Am Acad Dermatol. 2001, 45: 892-896.5.
Kantor GR, Bernhard J. Investigation of the pruritic patient in daily practice. Semin Dermatol. 1995, 14: 290-296.6.
Bernhard JD. Pruritus in skin disease. Bernhard JD(ed:) . Itch: Mechanisms and Management of Pruritus. New York:
McGraw-Hill, 1994, pp 37-67.
7.
Alonso-Llamazares J, Rogers RS III, Oursler JR, Calobrisi SD. Bullous pemphigoid presenting as generalized pruritus:
Observation in six patients. Int J Dermatol. 1998, 37: 507-514.
8.
Pujol RM, Gallardo F, Llistosella E, et al: Invisible mycosis fungoides: A diagnostic challenge. J Am Acad Dermatol.
2002, 47: S167-S171.
9.
Hagermark O, Wahlgren C. Treatment of itch. Semin Dermatol. 1995, 14: 320-325.10.
Back to Top
Pagina 9 di 10Pruritus
12/14/2011http://www.clevelandclinicmeded.com/medicalpubs/diseasemanagement/dermatology/pru...
7/28/2019 itch in medicine
10/10
Suggested Readings
Alonso-Llamazares J, Rogers RS III, Oursler JR, Calobrisi SD. Bullous pemphigoid presenting as generalized pruritus:
Observation in six patients. Int J Dermatol. 1998, 37: 507-514.
Bernhard JD. Pruritus in skin disease. Bernhard JD: Itch: Mechanisms and Management of Pruritus. New York:
McGraw-Hill, 1994, pp 37-67.
Greaves M. Mediators of pruritus. In: Bolognia JL, Jorizzo JL, Rapini RP (eds): Dermatology. St Louis: Mosby, 2003,
pp 85-94.
Hagermark O, Wahlgren C. Treatment of itch. Semin Dermatol. 1995, 14: 320-325.
Kantor GR, Bernhard J. Investigation of the pruritic patient in daily practice. Semin Dermatol. 1995, 14: 290-296.
Pujol RM, Gallardo F, Llistosella E, et al: Invisible mycosis fungoides: A diagnostic challenge. J Am Acad Dermatol.
2002, 47: S167-S171.
Stnder S, Steinhoff M, Schmelz M, et al: Neurophysiology of pruritus: cutaneous elicitation of itch. Arch Dermatol.
2003, 139: 1463-1470.
Stnder S, Weisshaar E, Mettang T, et al: Clinical Classification of itch: A position paper of the International Forum forthe Study of Itch. Acta Derm Venereol. 2007, 87: 291-294.
Ward JR, Bernhard JD. Pruritus. In: Lebwohl M, Heymann WR, Berth-Jones J, Coulson I (eds): Treatment of Skin
Disease. 2nd ed. St Louis: Mosby Elsevier, 2006, pp 533-537.
Zirwas MJ, Seraly MP. Pruritus of unknown origin: A retrospective study. J Am Acad Dermatol. 2001, 45: 892-896.
Editorial PolicyDisease Management Project Disclaimer
Copyright 2000-2011 The Cleveland Clinic Foundation. All Rights Reserved.Center for Continuing Education | 9500 Euclid Avenue, KK31, Cleveland, OH 44195
Main Cleveland Clinic WebsiteAccreditation with CommendationAwardsSite DisclaimerPrivacy PolicyFeedbackSitemap
Copyright 2000-2011 The Cleveland Clinic Foundation. All Rights Reserved.Center for Continuing Education | 9500 Euclid Avenue, KK31, Cleveland, OH 44195
Pagina 10 di 10Pruritus