Clinical and Etiopathological Study on Pityriasis Rosea.

INTRODUCTION : Pityriasis Rosea (PR) is a common dermatoses seen in dermatology out- patients department. It is an acute, self- limiting papulosquamous disorder with a distinctive and constant course. Ever since, it was first described, the interest in this disease was centred mainly on its varied morphology and obscure aetiology. Pityriasis Rosea has been reported in all races, with varying incidence between 0.3 and 3 percent. It is more common between 10 and 35 years of age, with equal sex distribution or a slight female preponderance. The disease is more common during autumn and winter with a decreased incidence in summer. It has been reported to occur among persons in the same intimate environment; a higher incidence also noted among dermatologists. Experiments by various workers to determine the cause of the disease have been unsuccessful. Fungus, bacteria, spirochetes, drugs, contact with new garments, psychogenic and neurogenic factors were all implicated in the causation of the disease. Currently a virus is believed to play a pathogenic role. The prodromal illness, generalised exanthem accompanied by constitutional reactions, spontaneous resolution and life long immunity, all point towards a viral cause. Extensive research has been carried out in patients with PR with respect to the newly identified Human Herpes Virus 6 and 7. The results from different studies however are found contradictory. It is thus possible and remains an unproved fact that HHV-6 and 7 may play a role extensively in some patients with PR. In its classical form, PR is a distinctive dermatoses which is readily identified clinically. The initial lesion is a herald patch or primary plaque that is followed after one or two weeks by a generalised secondary rash with a typical distribution parallel to the lines of cleavage of the skin, resembling a “Christmas tree”. The various morphological types observed are macular, papular, maculopapular, lichenoid, vesicular, pustular, purpuric, urticarial and Erythema Multiforme (EMF) like lesions. Though the lesions can occur anywhere on the skin it is rarely seen over the scalp, palms and soles. After a limited course of six to eight weeks the lesions resolve leaving a residual hypo or hyper pigmentation without any complications. AIM OF THE STUDY : To study - the incidence of pityriasis rosea in Government general hospital, Chennai during the period Aug 06 to Aug 08 - age and sex distribution - the various morphological patterns and distribution of skin lesions in Pityriasis Rosea - the course, total duration and complication of the disease - histopathology of skin lesions - associated skin diseases - culture of scales from the skin lesion to exclude bacterial aetiology. CONCLUSION : In this clinical and etiopathological study on Pityriasis Rosea done in Department of Dermatology, Madras Medical College and Government General Hospital, Chennai the following points were observed * Clinical diagnosis of Pityriasis Rosea was easy, based on the presence of Herald Patch, characteristic morphology and distribution pattern of the lesions. * The present study has revealed male preponderance. * The age incidence was found to be high in adolescents and young adults. * Familial incidence was also observed * The diseases was more frequent in the winter and rainy months with sporadic cases occurring throughout the year * Factors like wearing of new garments, pregnancy, stress and upper respiratory tract infections were found to precipitate the disease. * The Herald Patch was observed to occur in the covered areas of the body, mostly over the trunk. The secondary eruptions had a wide spectrum of morphological forms with a variable distribution. Localised Pityriasis Rosea were also observed in this study * Most of the patients had complete resolution of the lesions in 5 to 8 weeks but, lichenoid type of Pityriasis Rosea tends to persist for a longer duration. * In most of the patients the lesions vanished without trace and post inflammatory hypopigmentation was noted in few patient, but none had hyperpigmentation. * There was no complication in any of the patients. * Recurrence of the disease was also observed. * Histopathological study showed the features of non specific chronic dermatitis. * Culture of scales from the lesions did not show any bacterial growth. In conclusion most of the clinical and histopathological features were consistent with the findings reported in the literature