Background

This is the medical term for itching. It may be associated with underlying systemic illnesses or may be a bothersome itch. A persistent pruritis should always be investigated by a physician. This differs from urticaria which is associated with wheals, flares, and reddening. Nontheless, both conditions present with itching or pruritis.

Outline

Pathogenesis
Prognosis and Treatment
Commonly Used Terms

 

DISEASE ASSOCIATIONS	CHARACTERIZATION
Pruritus: pathogenesis, therapy, and significance in systemic disease states. Gilchrest BA.	Arch Intern Med 1982 Jan;142(1):101-5 Abstract quote Pruritus is a cutaneous sensation sharing neural receptors and pathways with pain but is characterized by its own precipitants, potentiators, and range of severity. Among patients with generalized pruritus, the prevalence of systemic disease has been reported as 10% to 50%, with renal, hepatic, hematopoietic, or endocrine causes most commonly identified. Malignant neoplasms, neurologic disorders, certain drugs, or advanced age also may be responsible. Although the pathogenesis of pruritus is unknown, clinically AG event potential mediators have been investigated in several settings. Therapy often fails when the underlying disorder cannot be corrected, but por pruritus associated with chronic renal failure or hepatic cholestasis, specific and usually effective treatments exist.
Severe itching in the patient with burns. Vitale M, Fields-Blache C, Luterman A. University of South Alabama Burn Center, Mobile	J Burn Care Rehabil 1991 Jul-Aug;12(4):330-3 Abstract quote After discharge, the patient with burns is often plagued with persistent, unrelenting itching. The purpose of this study was to document the incidence and severity of itching in discharged patients with burns, to determine factors that may help in prediction of the problem, and to study the effectiveness of Benadryl (Parke-Davis, Morris Plains N.J.), Atarax (Roerig Div. of Pfizer Inc., New York, N.Y.) and Polyhist Forte (Mikart Inc., Atlanta, Ga.) in relieving the symptom. All adult patients who were discharged to our outpatient clinic were entered into this prospective study. Patients were started on one of the three agents, and agents were changed monthly in a randomized fashion. Severity of itching was determined by a visual linear analogue scale. The study population had a mean age of 35.9 +/- 12.8 years, and a mean burn size of 19.1% +/- 15.3% total body surface area. Eighty-seven percent of discharged patients complained of itching. The average severity of the problem was 7.6 +/- 1.9. A significant difference (p less than 0.05) among groups was found when the population was analyzed for size of burn and duration of time to wound closure. Symptoms varied with anatomic area burned. One hundred percent of patients with leg burns and 70% of those with arm burns complained of itching. Facial burns did not cause itching in any of the patients. The agents that were tested produced complete relief in only 20% of patients, partial relief in 60%, and no relief in 20%. There were no differences in response to the three agents tested. All three of the drugs that were tested had similar onset of action.(
Pruritus in patients with chronic human immunodeficiency virus, hepatitis B and C virus infections. Bonacini M. Keck School of Medicine of the University of Southern California, Los Angeles 90033, USA.	Dig Liver Dis 2000 Oct;32(7):621-5 Abstract quote AIM: The prevalence of pruritus was prospectively determined in 310 patients of whom 119 had hepatitis C virus infection, 91 hepatitis C virus and human immunodeficiency virus, 51 human immunodeficiency virus infection alone, 31 hepatitis B virus and human immunodeficiency virus coinfection and 18 were HBsAg carriers. RESULTS: Patients in the first three groups were more likely to complain of itching (22%, 28% and 25%, respectively) than HBsAg carriers (8.2%, p=0.01. Laboratory data were not different between groups, except for the human immunodeficiency virus group, whose alkaline phosphatase levels were highest, and CD4 counts were lowest (median 30 cells/mm3). Patients with hepatitis C, including those with human immunodeficiency virus, had similar hepatitis C virus RNA levels in patients with or without pruritus. There was no difference in hepatic inflammation or fibrosis between those with and those without pruritus. CONCLUSION: 20% of patients with chronic hepatitis C and 8% of hepatitis B patients complain of pruritus. Patients with pruritus have laboratory and histologic parameters comparable to those without.
Pruritus of unknown origin: A retrospective study Matthew J. Zirwas, MD Mark P. Seraly, MD Pittsburgh, Pennsylvania	J Am Acad Dermatol 2001;45:892-6. Abstract quote Background: Pruritus of unknown origin is a common complaint, and systemic causes must be considered. However, there is little data on how frequently systemic causes are responsible or whether any patient characteristics make a systemic cause more likely. Objective: We attempted to determine how frequently pruritus of unknown origin had a systemic etiology in an outpatient population seen in a university dermatology department and whether any patient characteristics made a systemic explanation more likely. Methods: This is a retrospective study using chart reviews and telephone interviews to collect data. Results: Of 50 patients, 11 had a systemic cause of pruritus. Pruritus was the initial symptom of systemic disease in 7 of these patients. No patient characteristics were statistically associated with systemic causes of pruritus. Conclusion: Pruritus of unknown origin was the initial symptom of a systemic disease in 7 of 50 patients presenting to a dermatology clinic with this complaint. The underlying diseases included hypothyroidism, gastric adenocarcinoma, hepatitis C, HIV, laryngeal carcinoma, graft-versus-host disease, and chronic lymphocytic leukemia.

 

PATHOGENESIS

CHARACTERIZATION

Role of antigen-induced cytokine release in atopic pruritus. Lippert U, Hoer A, Moller A, Ramboer I, Cremer B, Henz BM. Department of Dermatology, Virchow-Klinikum, Humboldt Universitat zu Berlin, Germany

Int Arch Allergy Immunol 1998 May;116(1):36-9 Abstract quote In order to further evaluate the role of cytokines in the induction of atopic pruritus, leukocytes from 10 atopic eczema patients or 10 nonallergic controls were stimulated in vitro with mite or birch pollen antigen for 1 and 4 days. Subjects were prick-tested with the supernatants, and whealing and itching were evaluated 20 and 60 min later. The supernatants were also examined for the contents of GM-CSF, IL-2, IL-6 and IL-8 by ELISA and TNFalpha. Two hours prior to testing, the antihistamine cetirizine (20 mg) or a placebo tablet were given to the patients according to a randomized, double-blind study protocol. After pricking with antigen-stimulated leukocyte supernatants, 6 of 10 patients but no controls reacted mostly at 20 min with whealing and/or pruritus. In the cetirizine-treated group, no decrease in these skin reactions was seen compared to placebo. Analysis for cytokines showed increased levels of IL-8 in allergen-stimulated samples, with no correlation to the induction of itching or whealing by these supernatants. IL-6 levels were low and variable, and GM-CSF, IL-2 and TNFalpha levels were always below standard values. These data show that leukocytes selectively release IL-8 in response to in vitro antigen stimulation. They furthermore provide additional support for the concept that as yet to be identified products play a role in atopic pruritus.

 

PROGNOSIS AND TREATMENT	CHARACTERIZATION
PROGNOSTIC FACTORS
TREATMENT
Differential effects of new-generation H1-receptor antagonists in pruritic dermatoses. Henz BM, Metzenauer P, O'Keefe E, Zuberbier T. Department of Dermatology, Virchow Klinikum, Humboldt University, Berlin, Germany.	Allergy 1998 Feb;53(2):180-3 Abstract quote In search of an improved treatment of pruritic dermatoses, we have studied azelastine, a novel H1-receptor antagonist, during a 2-week treatment period, using a double-blind, placebo-controlled design. The potent H1-antagonist cetirizine was used for comparison. Symptoms were recorded daily by the patients on a diary card, using a 4-point scale. The same parameters and adverse events were evaluated at weekly intervals, and global improvement was evaluated at the end of treatment. In all 230 evaluable patients with moderate to severe itching, azelastine caused an overall significant improvement in comparison to placebo (P = 0.02), with significance also for pruritus (P = 0.01 after 1 week and P = 0.02 after 2 weeks). Both drugs reduced itching more effectively in urticaria than in atopic eczema. Azelastine was superior to cetirizine in reducing pruritus, whereas cetirizine caused a more marked reduction of whealing. Both drugs rarely caused fatigue and dry mouth, but taste perversion occurred only in azelastine-treated patients (9.7%) and headaches only with cetirizine (10.4%). Therefore, the two H1-blockers exert differential effects on pruritus verses whealing and a distinctive adverse events pattern. The data also underline the low efficacy of antihistamines in atopic eczema, compared to urticaria.
Cutaneous field stimulation in the treatment of severe itch. Wallengren J, Sundler F. Department of Dermatology, Lund University Hospital, SE-221 85 Lund, Sweden.	Arch Dermatol 2001 Oct;137(10):1323-5 Abstract quote OBJECTIVE: To evaluate the efficacy of cutaneous field stimulation of C fibers for the treatment of itchy skin and its effect on peripheral nerve fibers as shown in skin biopsy specimens. DESIGN: We conducted an open-label uncontrolled study of 19 patients with itching. Each patient applied a flexible plate containing electrodes to the itchy area for 20 minutes at a time once daily for 5 weeks to stimulate nerve fibers with a constant current (0.8 mA). Skin biopsy specimens were collected before treatment and at the end of treatment and were immunostained for calcitonin gene-related peptide and protein gene product 9.5. SETTING: University hospital in Lund, Sweden. PATIENTS: Sixteen patients with nostalgia paresthetica or brachioradial pruritus and 3 with generalized itch. INTERVENTIONS: Cutaneous field stimulation and punch biopsies of the itchy skin. MAIN OUTCOME MEASURES: Visual analog scale for assessment of itching and counting the immunoreactive nerve fibers in 3-mm biopsy specimens. RESULTS: Patients with localized itching experienced a reduction in mean values on the visual analog scale (from 78% before treatment to 42% by the end of the fifth week). The number of protein gene product 9.5- immunoreactive nerve fibers in the epidermis was reduced by 40% by the end of treatment compared with baseline values. CONCLUSIONS: Cutaneous field stimulation is an effective alternative for the treatment of localized itching. The reduction in itching is accompanied by degeneration of the epidermal nerve fibers, as evidenced by the loss of protein gene product 9.5 immunoreactivity.
Comparison of the effects of levocetirizine and loratadine on histamine-induced wheal, flare, and itch in human skin. Clough GF, Boutsiouki P, Church MK. Dermatopharmacology Unit, Allergy and Inflammation Sciences, School of Medicine, University of Southampton, Southampton, UK.	Allergy 2001 Oct;56(10):985-8 Abstract quote BACKGROUND: This randomized, double-blind, crossover study compared the effects of the R-enantiomer of cetirizine, levocetirizine, with those of loratadine on the wheal, flare, and itch response to histamine in human skin. METHODS: Levocetirizine (5 mg), loratadine (10 mg), or placebo was taken orally 4 h before the intradermal injection of histamine (20 microl, 100 microM) or the control vehicle into the forearm skin of healthy volunteers. Flare areas were assessed by scanning laser Doppler imaging before and at 30-s intervals for a period of 9 min. Wheal areas were measured by planimetry at 10 min. Itch was scored every 30 s with a visual analogue scale. RESULTS: After placebo administration, the mean peak flare area was 23.01+/-1.94 cm(2), the wheal area 248+/-27 mm(2), and the cumulative itch score 28.8+/-4.6% (mean+/-SEM). Levocetirizine reduced the flare, wheal, and itch by 60%, 68%, and 91%, respectively (all P<0.001, Student's t-test for paired data). The effects of loratadine were variable and not statistically significant. CONCLUSION: Levocetirizine (5 mg) is a potent inhibitor of the effects of histamine in human skin with an efficacy that exceeded that of loratadine (10 mg) when single doses of the drugs were administered 4 h before the test.

Weedon D. Weedon's Skin Pathology. Churchill Livingstone. 1997.
Fitzpatrick's Dermatology in General Medicine. 5th Edition. McGraw-Hill. 1999.

Skin

Urticaria and Angioedema

Last Updated 11/24/2001