:خارشعالمت پوستی است که به درجات مختلفی در انواع شایع ترین -

.درماتوزها و نیز گاهی دربیماریهای داخلی دیده می شود- یک حس ناخوشایند در پوست )و گاهی مخاط و خارش

قرنیه(است که.بیمار را وادار یا متمایل به خراشیدن یا مالیدن پوست می کند

شامل: محرکهای مختلف حس خارش توسط شیمیایی،حرارتی،مکانیکی، الکتریکی و نیز لمس

.سطحی،تغییرات دما و استرس ایجاد یا تشدید می شود

که نزدیک انتهاهای عصبی حس خارش و درد توسط جانکشن درم و اپیدرمال است،دریافت می شود.

، انتقال دهنده خارش از رسپتورهای فیبرهای سی پوستی بوده که این فیبرهای پلی مودال و غیرمیلینه وارد

سیناپس کرده و پس نرون ثانوی شاخ خلفی نخاع شده و با از تقاطع، از راه اسپینوتاالمیک به تاالموس رفته و از آنجا

،حس خارش را به کورتکس می بردنرون سوم .

Histamine receptorsH1 (smooth muscle, endothelial cells ,nerve

fibers ,acute allergic responses) H2( gastric parietal cells secretion of gastric

acid , T helpers)H3 (central nervous system,presynaptic

neurons modulating neurotransmission )H4 (mast cells, eosinophils, T cells, dentritic

cells regulating immune responses)

Is the most common symptom of patients coming to dermatologic clinics.

Causes:1-skin disease: (Lichen planus, pediculosis,

Scabies, Atopic dermatitis,Urticaria,…)

mild to moderate :psoriasis, seborrhea, photodermatitis

severe: lichen planus, atopic, neurodermatitis

Rubbing: urticaria, lichen planus, post menopause

2-Systemic.D: (CRF,CBD,…(3-Senile & winter .P

Systemic causes of pruritus

1-Chronic renal failure

Most of CRF patients & 80% of hemodialysis patients have pruritus.

The cause is unknown (uremia, dry skin ,increased skin mast cells & histamine release, secondary hyper parathyroidism,aluminium overload [treatable by desferrioxamine] ,hypervitaminose A, neuropathy, substance –P, serotonin, ….)

:خارش کلیویارتباطی با سن،جنس،نژاد،مدت دیالیز و علت نارسایی کلیه -

.ندارد. از همودیالیز ایجاد خارش می کندکمتردیالیز صفاقی -

پس از همودیالیز است و شبها شدیدتر می دو روز اوج خارش، - .شود

Treatment:-EmollientUVB therapy (depletes the vit.A )-Activated charcoal (6g/d for 8wks)

-Renal transplantation - parathyroidectomy, Heparin, lidocain

(200mg in 100cc normal saline slow iv infusion) , mexiletine, ion-change resins, topical capsaicin 0.025% 3-5 times daily

-Antihistamines & topical steroides not helpful

…Treatment:Topical gamma-linoleic acid (2.2%, 4 times daily)Gabapentin(200-300 mg after each hemodialysis

session)Cholestyramine (4-16g po qd in divided doses 30

minute before meal)Ondansetron (4-8mg iv, then 4mg orally every 8 hours)Nalfurafine (kappa-opioid receptor agonist): 5 micro g

iv 3 times a wk (post hemodialysis)Ketotifen (1-2 mg po qd)Thalidomide (100 mg po qd)Erythropoietin (36 U/kg sc 3 times a wk)

Treatments for pruritus of chronic renal failure.

2-Cholestatic biliary disease

In 20-50% of cholestasis & hepatitis C & other hepatitis , primary biliary cirrhosis, primary sclerosing cholangitis, obstructive choleducholithiasis, carcinoma of the bile duct

Generalized, migratory, not relieved with scratching

Worse on the hands & feet and body regions constricted by clothing, at night

In chronic cholestasis: can be early symptom developing years before any other manifestations.

Cause: unknown, percipitation of specific bile salts with specific concentration in skin.(not always)

- Increased opioidergic neurotransmisson or neuromodulation in the CNS (opiate agonists induce opioid receptor-mediated scratching activity of central origin)

Treatment:-Cholestyramin (powder=4g) 3 times 30

minute before mealmay be improved pruritus in PCV & uremia

+ rifampicin (10mg/kg/d or 300mg Bid), -UVB phototherapy

Naloxone (1ml=0.4mg) 0.8ml IDPlasmapheresisRibaverin : in chronic hepatitis C liver transplantation

Terfenadine & cholestyramine Phenobarbital (2-5 mg/kg/d) & rifampicin,

ondancetronAntihistamine? (sedation)Gabapentine?

Treatments for hepatobiliary pruritus.

NaltrexoneMu-receptor opioid

Antagonist

chronic pruritus of different origins(Post –burn Itch,MF ,Drugs (starch) ,prurigo nodularis,Chronic urticaria,Atopic derm.

Topical Doxepin:

Doxepin is a topical tricyclic antidepressant used for the relife of pruritus & pain.

Antihistamine (both H1 & H2 receptors) with anticholinergic properties.

Indicated for moderate pruritus in patients with atopic & LSC & other forms of dermatitis & neuropathic pain (sometimes in combination with topical capsaicin)

Cream 5% , 4 times a day for 7-8 daysSide effects: burning, irritation, allergic C.D,

drowsiness (in 20%) & sedation.Contraindications: category B, sensitivity, narrow

angel glaucoma, urinary retention, with MAO inhibitors

Topical capsaicin:A natural constituent of red chili peppers.Antipruritic & analgesic by desensitizing

nerve endingsEffects on the peripheral sensory nerve

endings by depletion substance-p from C fibers. (substance-p mediates pain impulses from peripheral sensory neurons to the CNS)

With repeated use: prevent heat, pain & itch sensation.

Therapeutic effect is observed after 1 wk

…Topical capsaicinIn intractable localized pruritus (prurigo

nodularis, brachioradial pruritus), uremic pruritus, superficial pain due to PHN , diabetic neuropathy, notalgia paresthetica, pruritus ani, psoriasis

Cream,gel, lotion 0.025- 0.075%, 4 times a day.Side effects: category C , itching, burning,

erythema (diminish with frequent use)

…Others:Gel pramoxine (1%): partial anesthesia (after few

minutes) for 2-4 h effect (combination with 0.5-2.5% hydrocortisone as a lotion, foam, cream or ointment)

Side effect: very low sensitization potentialCamphor (0.25-0.5%): is a ketone with a local

anesthetic effect & mild degrees of pruritus or burning.

Phenol: should not be used in pregnancy & infants less than 6 mo.

Menthol(0.025-0.5%): alcohol compound derived from mint (cooling effect as a result of its low boiling point)

Emollients: urea (10-20%), lactic acid (5-12%)

3-Iron deficiency anemiaIron deficiency: generalized or localized

(especially of the perianal or vulvar region)

Treatment of choice : Iron supplement

4-Malignancy

The rate of malignancy in patients with pruritus of unknown origin is the same as normal population except for :

Hodgkin lymphoma & poly cythemia vera - Obstruction of the biliiary tree, particularly in palms &

soles (carcinoma of the head of the pancreas or bile duct) - “Central pruritus” in brain tumors or as a consequence of

treatment (surgery, radiotherapy, chemotherapy) - Tumors of the brain: localized pruritus of the nose

Pruritus in Hodgkin lymphoma25% of Hodgkin's patients have pruritus. Pruritus is Bizarre & Migratory. Severe,

persistent generalized pruritus=recurrence of tumor or poor prognosis (B symptom)

- Due to release of histamine (from basophils), leukopeptidases or bradykinin, eosinophilia, occasionally hepatic involvement with lymphoma

Specific treatments for lymphoma. - Topical steroids - Oral mirtazapine (7.5-30 mg/d)

Non –Hodgkin lymphoma: Less prevalent( 2%), 10% of patients will suffer

from pruritus, in the course of disease. - Treatment: INF-a systemic

Leukemia: - Not common (usually generalized) Most commonly with CLL (in addition can develop

exaggerated reactions to insect bites) Paroxetine (selective serotonin reuptake

inhibitor in treatment of intractable pruritus such as advanced cancer)

Pruritus in PCV30-50% of patients have pruritus.Pruritus begins after exiting from water & lasts

30-60 minute(aquagenic pruritus)The best treatments are:1-Anti-PGs(aspirin 300mg qd TID) rapid relief it

provides for 12-24 h2- UVB or PUVA3- IFN-a IM 4- Antihistamines H1 or H2 receptors

Antiserotonins(cyproheptadine)?

5-Aquagenic pruritusThe clinic is the same as PCV.

1/3 of patients have positive family history.

The treatment is the same as PCV.

6-Endocrine disorders (1-thyroid) Localized P:…

candidiasis

A-hypothyroidism Generalized P:…xerosis

Localized P:….candidiasis

B-hyperthyroidism Generalized P:…

warmness of skin

Endocrine (2-Diabetes mellitus) generalized pruritus? scalp…neuropathyOnly localized.P genital…candidiasis.

Endocrine(3-Postmenopausal syndrome)

local ( in genital) or generalized with hot flushing. evokes Rubbing. Treatment with ethinyl estradiol (with anti

Candida)

7-Immundeficiency(AIDS)

Pruritus is one of the most prevalent symptoms in both specific & non-specific dermatitis associated with HIV (Scabies, pediculosis, seborrhea, candidiasis,…)

-Eosinophilic folliculitis

8-PrenancyAbout 2-20% of pregnant women have P.The most common cause of pruritus is

cholestasis.Pruritus is one of the most common

symptoms in both specific & non-specific dermatosis of pregnancy.

9-Neurological disordersBrain tumorsSpinal cord lesionsBrain abscessMultiple sclerosisNeuropathies(Notalgia paresthetica)etc

10-Psychologic disordersAnxietyDepressionStressHystericsPsychotic disorders parasitophobia,

(treatment with pimozide, Risperidone, Olanzapine,….)

etc

11-Drugs

Mostly:Opiates,Phenothiazines,Aspirin Tolbutamide,Erythromycine esteolate, Anabolic hormones (esterogen,Progestron, Testosteron),Vit B-complex,…

Note: 1-Every drug with idiosyncratic reaction can cause pruritus.

2-Drugs can cause pruritus months after the initiation of use.

Evaluation of patients with pruritus of unknown origin1-Complete skin examination2-History(drugs,internal disorders ,

contact with animals, chemicals,..)3-Systemic review4-Physical examination

(adenopathy,organomegally)

..Evaluation of patients with pruritus of unknown origin5-Screening tests (CBC, LFTs,

RFTs,TFTs, Chest-X ray, stool occult blood)

6-Other necessary tests7-Repeated history & Physical exam.8-Psychiatric assessment9-Periodic fallow up

Winter pruritus:

Only in winter,but in any age.Cause:xerosis due to overhydration

&using strong detergents.Clinic: xerosis & criss cross pattern

especially on legs & arms.Exacerbating of lesions after bathing.Treatment: glycerin soap & emollient

Senile pruritus:50% of elderly(>70Y) have senile .P.In every seasons.Cause & clinic is the same as winter's.But other precipitating factors are: -Drugs like diuretics,.. -Hypothyroidism -Protein & Zinc deficiency,…

Treatment of pruritusNo specific treatmentA- General measures: restriction of scratching, emotional stress,

intake of caffein,caffe, tea , choclate,cola drinks,alcohol.

B-Topical treatments: -Ice compress -starch bath- menthol, phenol ,comphor lotions

Continue- emollients- Anesthetics(only promoxin)- Doxepin cream- Capsaicin cream

4-Physical modalitiesUVBPUVATENS (Trans cutaneous Electric Nerve

Stimulation)Acupunctureetc

UV phototherapy UV phototherapy is used to treat various

pruritic conditions including:CRFAD; HIV; Aquagenic pruritus; Solar, chronic, and idiopathic urticaria; Urticaria pigmentosa; polycythemia vera; pruritic folliculitis of pregnancy;Breast carcinoma skin infiltration; Hodgkin’s lymphoma; Chronic liver disease; Acquired perforating dermatoses,

delusions of parasitosis most common in senile women

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