الفهرس 
Pityriasis RoseaOnly 14 pages are availabe for public view
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Abstract
Pityriasis Rosea (PR) is a common acute self limited skin eruption with a distinctive and constant course. The initial lesion is a primary plaque that is followed after 1 or 2 weeks by a generalized secondary rash with a typical distribution lasting for about 6 weeks. The prevalence of this disorder 0.13 percent in males and 0.14 percent in females, most patients being in the age group of 10 to 43 years. The incidence at different dermatologic centers has varied between 0.3 and 3 percent.
The exact etiology of the disease is uncertain, but various hypotheses have been postulated; incriminating infective agents such as viruses, fungi, streptococci and spirochetes and non infective etiologies such as atopy and autoimmune causes have also been investigated. It has been shown that PR may be associated with the reactivation of human herpes virus 7 (HHV-7) and sometimes human herpes virus 6 (HHV-6).
In 80 % of cases of PR the eruption of the disease follows a distinctive and remarkably constant pattern and course. It manifests initially with a herald patch, followed by the development of a generalized secondary eruption. In about 20% of patients with PR, the clinical picture diverges from the classical one; being atypical in the morphology, or distribution and or in its course. Several atypical morphologic presentations of the solitary element of the secondary eruption of PR occur including: macular, papular, vesicular, pustular, urticarial, purpuric, lichenoid lesions, erythema multiforme-like lesions and even exfoliative dermatitis.
There is no histopathologic feature pathognomonic for PR, however there are four characteristic signs which may be helpful in the differential histological diagnosis or may even permit a suspect diagnosis.Eczematoid Pattern (Unna’s sign), absence or decrease of granular cell layer, erythrocytes in the papillary dermis and partly into the epidermis and homogenization of the papillary collagen. By electron microscopy, there are herpes virus-like particles in PR lesional skin. Viral particles are seen in a large numbers among the collagen fibers in the upper and middle dermis close to the blood vessels. Virions are also interspersed among keratinocytes in the vicinity of the dermal-epidermal junction. Occasionally, viral particles detected within the cytoplasm of basal keratinocytes and degenerating cells.
The diagnosis of PR can usually be made on the basis of history, distribution of the skin lesions, and the individual lesion morphology. The presence of a herald patch is helpful, but may be infrequently observed. Rarely the skin biopsy is necessary. There are no laboratory studies of diagnostic importance.
It is important to do serological examination for syphilis for every case of PR, especially in those not having herald patch, in order to avoid any misdiagnosis between syphilis and PR especially in sexually active individuals, also It is important to do a potassium hydroxide (KOH) preparation of skin scraping for the lesions to be examined under the microscope searching for any hyphae and spores to clear out any confusion between PR and tinea circinata.
As pityriasis rosea is self limited, there is no need for active treatment in uncomplicated cases. Reassurance and symptomatic therapy are required in most of the cases. Some patients need treatment because of their extensive lesions or their annoying pruritus. No specific therapy is available.
When there is itching, zinc oxide, calamine lotion, Topical corticosteroid creams and short acting oral antihistamines are appropriate and often are helpful. In the widespread, severe forms, including vesicular PR, topical corticosteroid is indicated and exceptionally a brief course of an oral glucocorticoid preparation. Oral Erythromycin (1g daily in 4 equally divided doses for 2 weeks in adults) has been shown to clear PR in 2 weeks.
Application of ultraviolet B (in both broadband and narrowband) as well as low dose Ultraviolet A1 phototherapy in patients with PR substantially decreases the severity of the disease and can result in total recovery.
High-dose oral acyclovir (800 mg five times daily for 1 week) or even in low dose (400 mg five times daily for 1 week) used early after the onset of the eruption, may lead to a more rapid clearance of skin lesions.
Although the exact mechanism of UVB phototherapy in pityriasis rosea is unknown, there have been reports that lesions do not occur in the body areas where UV radiation is utilized. Therefore, UV radiation through an artificial source or by intentional exposure to natural sunlight has been recommended to decrease the duration of rash and the intensity of itching in patients with PR.
The suppression of cell mediated immune response and modification of the number and function of Langerhans cells in the skin following UV irradiation may at least partly explain the beneficial action of UVB light on this disease.
The most frequent side effect is dermatitis solaris due to an excessive UVB dose. In case of inadequate eye protection, conjunctivitis and keratitis can occur. As with other forms of UV exposure, in addition to the expected immediate sunburn effects, chronic NB-UVB exposure is likely to increase photo aging and the risk of carcinogenesis but this only happens when used as a long time therapy.
.On the other hand, there is a probable aetiological role for HHV-6 and HHV-7 or both in PR .The detection of HHV-7 and HHV-6 DNA or both in peripheral mononuclear cells, tissues and in cell free plasma of PR patients corresponding to active viral replication supports a causal relationship, so it is possible that an effective treatment against these viruses may help in reduction of severity of this disease.
Acyclovir in high doses (800 mg five times daily for 1 week) has an anti HHV-6 effect while it shows little activity against HHV-7in vivo and vitro. In addition, Acyclovir has much less side effects than other effective anti viral drugs such as gancyclovir, foscarnet and pencyclovir.
The aim of this thesis is to evaluate the clinical efficacy of narrow band UVB versus oral acyclovir in the treatment of pityriasis rosea.
This study is done on 40 patients with ages ranging from 18 to 34 years suffering from pityriasis rosea who had not received any systemic or topical treatment for existing or any other condition. Patients were divided into two groups. The first group included 20 patients treated with NB-UVB three times/week. The second group included 20 patients treated with oral acyclovir (800mg given 5 times daily for 7 days). The patients were compared to a third control group which included 20 patients who were treated by topical emollient. All patients in all groups were followed up until the clearance of the lesions (a patient had a PRSS score of 2 or less).
There was no statistical significant difference between different studied groups as regards the Gender , skin type , age (years), disease duration (days) and initial PRSS score.
The overall rash improvement assessed by the reduction in PRSS score was statistically significant more for patients in UVB and oral acyclovir groups than patients in emollient group but there was no significant difference between UVB and oral acyclovir groups from the 1st to the 4th week.
There was a statistical significant increase in the number of patients in UVB and oral acyclovir groups who showed clearance of lesions than in the emollient group but there was no significant difference between UVB and oral acyclovir groups from the 2nd to the 4th week.
There was no statistical significant difference between different studied groups at the end of the 5th week.
Our results therefore show that UVB and oral acyclovir treatment did not change the final course of the disease as PR is self limited but can lead to hastening of involution and more rapid clearance of lesions.
In conclusion, this study shows a comparable efficacy of both NB-UVB and oral acyclovir in the treatment of PR with minimal reversible side effects. Consequently, narrow band UVB phototherapy and high-dose acyclovir (800 mg five times daily for 1 week) can be regarded as therapeutic options in the treatment of PR especially in patients with extensive lesions to hasten involution and reduce of the time of clearance of lesions.