Nummular dermatitis often begins with extremely dry skin. Patches of blister-like spots develop, and eventually the rash forms into patches. The coin-shaped patches, which are the defining symptom of the condition, are usually well-defined circles. This causes the rash to form a ring shape that looks similar to a ringworm infection. The rash eventually may form a yellowish crust, especially if it becomes infected. After a few days, the lesions and surrounding areas may become dry and scaly [source: Miller].
The patches of lesions, which can be red, pink or brown, are usually itchy and sometimes cause a burning or stinging sensation that worsens at night. The number and size of the patches and the duration of the outbreak can vary [source: American Academy of Dermatology]. After the first appearance of lesions, nummular dermatitis can become chronic and recur frequently. The lesions may last a few weeks and then disappear, but they can come back several weeks or months later [source: American Osteopathic College of Dermatology]. The lesions often reappear in the same places as the old ones, and even though the lesions may heal, they often leave scars [source: Miller].
It can be difficult to distinguish nummular dermatitis from other types of dermatitis, but similar treatments are used to treat various types of the condition. Read on to learn more about these treatments.