This information is provided by the National Institutes of Health (NIH) Genetic and Rare Diseases Information Center (GARD).
Pityriasis rotunda is a rare skin disease characterized by round, scaly, pigmented patches that mainly occur on the trunk, arms and legs. There are two types of pityriasis rotunda. Type 1 is seen mainly in East/Southeast Asian and South African individuals older than 60 years, and is often associated with internal disease or malignancy (cancer). Type 2 occurs in lighter skinned individuals younger than 40 years, and often in several members of the same family. Type 2 pityriasis rotunda is not associated with internal disease or malignancy. The cause of pityriasis rotunda is unknown, but it may be a variant of ichthyosis vulgaris. Type 1 most often occurs with liver and stomach cancer.
For more information, visit GARD.