Familial pityriasis rotunda.

Pityriasis rotunda is a rare dermatosis characterized by circular, dusty scaling, dyschromic patches, quite asymptomatic and mostly described in Japanese and blacks. The authors have seen three cases of pityriasis rotunda in a Sardinian family that are to be added to two other similar reports. The patients were all in good health. An interesting feature was the association with favism. On inquiry it was discovered that many more members of the family were affected by either or both pathologies. The authors believe this condition to be a form of minor acquired ichthyosis of which Sardinia could be an ethnic center.