Mondo Description Necrobiosis lipoidica is a rare skin disorder of collagen degeneration. It is characterized by a rash that occurs on the lower legs. It is more common in women, and there are usually several spots. They are slightly raised shiny red-brown patches. The centers are often yellowish and may develop open sores that are slow to heal. Infections can occur but are uncommon. Some patients have itching, pain, or abnormal sensations. It usually occurs more often in people with diabetes, in people with a family history of diabetes or a tendency to get diabetes, but can occur in nondiabetic people. About 11% to 65% of patients with necrobiosis lipoidica also have diabetes, but the exact cause is still not known. Treatment is difficult. The disease is typically chronic with variable progression and scarring.