Pityriasis rotunda sardoa Studio clinico, epidemiologico e follow-up su 47 casi osservati nel nord Sardegna dal 1981 al 1995

Background. Pityriasis rotunda (PR) is a dischromic and squamous dermatosis of unknown aetiology. At present we think that at least two different clinical-evolutive forms of this entity are described in the literature. The adult form is frequently associated with malignant tumours and/or infections and is more frequent in blacks. The classic form originally described in Japan arises usually in children and is not associated with systemic nor neoplastic diseases; the lesions are hypopigmented and squamous and usually disappear during adolescence. Materials and methods. In 1981- 1995 period we observed at the Department of Dermatology of the University of Sassari, 47 patients (27 females and 20 males) affected by typical patches of PR. Twenty-two (47%) were children, 18 (38%) were adolescents, seven adults (15%). Only two patients were over thirty. The skin lesions, never itchy, began in 80% of the patients between 2 and 7 years of age and only in a few cases over 10. Most frequently involved sites were: trunk, upper limbs, lower limbs. The number of lesions varies, in our cases, from 4 to more than 200 and their diameter changes from 2 mm to 10 cm; 39 cases (83%) are familiar, spread into twenty-one not related families. Results. Mycologic and bacteriologic investigations were always negative. Atopy and cutaneous xerosis were associated in 28 patients and 3 cases were associated with ichthyosis vulgaris. The course of the disorder, varied from five to eleven years. PR recovers spontaneously very slowly but completely and without scars after puberty in most cases, particularly after sixteen years of age. Conclusions. Our observations agree with previous studies on the epidemiology and clinical evolution of pityriasis rotunda in Sardinia and seem to demonstrate that this disease is a rare endemic genodermatosis due to ancestral phenomena of isolation of the population in the island and, for this reason, the peculiar form of Sardinia is named pityriasis rotunda sardoa.