A dermatologist usually makes a diagnosis of discoid eczema, based on the person’s medical history and by examining the skin.
If there is doubt about the diagnosis or it does not have a classical appearance, a skin biopsy may be needed.
A swab may be needed to determine if a bacterial or viral infection is also present.
Patch testing for dermatitis may be needed if a person’s history suggests that they are in contact with a material that may be causing the condition.
There are no routine blood tests.