Pityriasis rosea unilateralis

BK Brar, A Pall, RR Gupta

 Dept. of Dermatology, Venereology & Leprology, Govt. Medical College & Hospital, Faridkot - 151 203, Punjab, India

Correspondence Address:
B K Brar
C/o. Brar Eye Hospital, 637, Street No. 4, Lajpat Nagar, Kotkapura - 151 204, Punjab
India

Introduction

Pityriasis rosea (PR) is an acute, self limiting skin eruption characterized by distinctive and constant course with minimal constitutional symptoms. Classically, it presents as a primary plaque (herald patch) which is followed by a generalized secondary rash after 1 or 2 weeks. In about 20% of patients the picture diverges from the classical one.′ Unilateral variant of PR is very rare. The present cases are reported because of the rarity of the condition.

Case Report

Case 1: A 20-year-old male presented with well defined, oval, hypopigmented plaques with central wrinkled areas over the left side of back since 5 days. The lesions had an erythematous peripheral zone which at few places was separated by collarette of fine scaling. The herald patch was absent [Figure - 1].

Case 2: A-25- year old female presented with well-defined salmon coloured plaques over the right forearm since seven days. The lesions were accompanied by mild itching. Patient first noticed a plaque over the wrist which was followed by new plaques of various sizes. On examination, two big plaques were present on the wrist and middle part of forearm with small lesion present in between. At places lesions were merging with one another. Some lesions showed typical collarette of scales [Figure - 2].

In both cases, there was no history of insect bite, or drug intake. KOH preparation for fungus was negative. Lesions remained unilateral and no new lesions were seen during follow-up. The routine tests were normal and the histopathological findings were consistent with the diagnosis of pityriasis rosea.

Discussion

Pityriasis rosea is characterized by erythematosquamous lesions usually confined to trunk, the base of the neck and the upper third of the arms and legs. Infectious agents (staphylococcus albus, spirochaetes, beta-hemolytic streptococcus, mycoplasma, picorna virus) drugs and environmental factors have been implicated in its pathogenesis. Many variants viz., plaques, urticaria, vesicles, bullae, lichenoid lesions, non--palpable purpura, wrythema multiforme-like lesions, gigantic plaques and even exfoliative dermatitis have been reported.[2] Pityriasis rosea unilateralis has already been reported by Delcampo and others.[3],[4] The eruption appeared in crops in both cases and became confluent in case 2. In both patients the lesions tended to remain localized.

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