If a person has at least three of the following symptoms, they are diagnosed as having the condition:

• Being older than 16 when the symptoms appear
• Having taken medications before the symptoms appeared
• A slightly elevated, purple-red rash over one or more areas of skin. The rash doesn't whiten when pressed.
• Flat and raised lesions of different sizes over one or more areas of skin
• Changes in the cells of the small blood vessels that can be seen through a microscope

A doctor will do a physical examination and ask about symptoms. He or she will rule out Henoch-Schönlein purpura as a cause of the symptoms.

There is no specific treatment for this disorder. Most cases disappear without treatment. If symptoms persist, therapy with corticosteroids such as prednisone is usually tried.