What causes inflammation of the skin with an unknown diagnosis?

Inflammation: There are hundreds of different causes of inflammation of the skin one of the jobs that a dermatologist has is to discover the cause of the inflammation in a particular patient. Some cases are easier to discover than others. Sometimes blood tests and skin biopsies are helpful in establishing a diagnosis.

Numerous reasons : There are over 2000 named skin conditions and rashes and new ones have been described and discovered even in the past few years. If a rash is persisting and has an unknown cause, lab work and a small skin biopsy can often help diagnose the condition. See a dermatologist for evaluation and treatment.

Usually: Usually a biopsy will tell what type of inflammation.