Pityriasis rotunda

Iffat Hasson¹ , Parvaiz Shah²

¹ Dept. of Skin, STD & Leprosy, Institute of Medical Sciences, Medical College, Bermina, Srinagar - Kashmir, India
² Dept. of Medicine, Govt. Medical College and Associated SMHS Hospital, Srinagar - Kashmir, India

Correspondence Address:
Iffat Hasson
Firdousabad Batmaloo (Tengpara Road), Srinagar, Kashmir
India

Introduction

Pityriasis rotunda is disorder of keratinization characterized by geometrically perfect circular sharply defined patches of dry ichthyosiform scaling. It is relatively common in the Far East where it accounts for some 0.2% of dermatological cases. It has also been reported in South Africans, Bantus and in West Indians living in London. It is very rare in Caucasoids but a typical case has been described in an Israeli Caucasian woman.

The exact incidence and geographical distribution of this disorder are unknown. It is postulated that a geographical distribution of this disorder are unknown. It is postulated that a genetic factor is involved, but systemic illness and perhaps pregnancy, appear to favour the development of lesions which may previously have been latent. It has been reported that in two patients the condition appeared to be a cutaneous marker of malignancy.[1]

Case Report

A 13-year-old girl of a consanguineous marriage presented with complaints of scaly lesions over the back and legs of four year duration. There was no history of itching or oozing from the lesions. On further probing, there was no history suggestive of a illness. Family history was noncontributory.

Cutaneous examination revealed slightly pigmented well defined circular patches varying in size from 2-10 cms in diameter present on back, buttocks, legs and the volar aspect of left wrist. The lesions were sharply defined however, over the buttocks the lesions had coalesced to form bigger patches. The lesions were dry and scaly. Erythema and induration were absent. Examination of the mucous membranes, hair and nails did not reveal any significant finding. The patient′s general physical examination and systemic examination were non contributory.

Routine investigations like hemogram, urinalysis, liver function tests and renal function tests were within normal limits. Chest skiagram and ultrasonographic scanning of abdomen and pelvis were normal. Direct microscopic examination of scales prepared with potassium hydroxide was negative. Histologic features of a skin biopsy specimen were thought to be consistent with a diagnosis of pityriasis rotunda. The patient was treated topically with steroid salicylic acid and emollients with some relief.

Discussion

Pityriasis rotunda was described previously as pityriasis circinata and acquired pseudoichthyosis.[2] The lesions of pityriasis rotunda are often perfectly circular, sharply defined patches of dry ichthyosiform scaling usually 2-3 cm in diameter but sometimes much larger. They are commonly situated on the buttocks, thighs, abdomen, back or upper arms and may be solitary or multiple. They develop between the age of 25 and 45 (7 and 76 are the reported extremes) and remain unchanged throughout life. The age of onset, distribution, strikingly circular outline and complete lack of inflammatory changes should suggest the diagnosis.

The pathogenesis of pityriasis rotunda remains an enigma. Morphologically, the lesions bear a superficial resemblance to finea corporis. Morphologically, the lesions bear a superficial resemblance to tinea corporis. However, all attempts to demonstrate an infective origin (either bacterial or fungal) have been unsuccessful. Pityriasis rotunda also occurs in association with diseases of the female genital tract (e.g. uterine myomas, fibroids, ovarian cysts and in patients with a macerated fetus) and in miscellaneous chronic illnesses. In two patients the condition appears to be a cutaneous marker of malignancy.[2],[3],[4]

Another perplexing feature of pityriasis rotunda is the racial distribution of the disorder. It is rare in caucasoids, common in Japanese and is also seen in South African blacks and West Indian black. However, pityriasis rotunda has not been described in the American black which is surprising as the Jamaicans and American blacks have a common racial origin. HLA studies of these patients would be of interest.

Our patient had pityriasis rotunda at an early age (13 years), although it usually occurs between the ages of 25 and 45 and there was no apparent association with any systemic illness. Pityriasis rotunda has not been reported so far from this part of the world.

1.	Griffiths WAD, Judge MR, Leigh IM. Disorders of keratinization. In: Rook/Wilkinson/Ebling Textbook of Dermatology. Champion RH, Burton JL, Burns DA, Breathnach SM eds. Blackwell Science, London, 6th edition 1998, vol 2 pg 1530. [Google Scholar]
2.	Ito M, Tanaka T Pseudo ichthyose acquire an taches circulaires. Ann Dermatol Syphiligr 1960; 87: 26-37. [Google Scholar]
3.	Findlay GH. Pityriasis rotunda in the South African Bantu. Br J Dermatol 1965;77: 63 - 64. [Google Scholar]
4.	Leibowitz MR, Weiss R, Smith EH. Pityriasis rotunda. A cutaneous sign of malignant disease in two patients. Arch Dermatol 1983; 119: 607-609. [Google Scholar]