Pityriasis rotunda: a survey of 42 cases observed in Sardinia, Italy.

Background: Pityriasis rotunda (PR) is an uncommon dermatosis characterized by multiple, round or oval, sharply demarcated scaling patches that are dyschromic and asymptomatic. It has been described in Japanese and in blacks, usually in association with certain infective or malignant systemic diseases.
Objective: The aim of this study is to further clarify this rare entity which in Italy seems to be confined to the island of Sardinia.
Methods: We studied 42 Sardinian patients, 22 males and 20 females, in an age range of 3-32 years. In 29 cases, the disease involved more than one family member. The patients were observed in Cagliari, the capital city of Sardinia.
Results: Bacterial, viral and fungal investigation yielded negative results. Haematochemical and immunological examination and thyroid, hypophyseal and adrenal hormones did not reveal any alterations. No systemic pathologies were found associated with the disease.
Conclusions: The cases studied by us and those previously reported seem to indicate the presence of two distinct types of PR with significant prognostic differences.