Seborrheic dermatitis can be diagnosed clinically by taking a thorough medical history, and physical examination of the skin areas that are affected. In most cases, however, tests are not required. Tests are usually done when the diagnosis is not clear or some other medical condition is suspected to be cause of your skin problem.
Medical history and physical examination: Your doctor may ask questions such as:
The doctor will examine your scalp and other parts of the body (such as the face, back, chest) and look for findings suggestive of seborrheic dermatitis. Some features of seborrheic dermatitis noted on examination are:
Some tests that may be done to diagnose the cause of your skin problem include skin scrapings, microscopic evaluation, blood tests, and skin biopsies.
Skin scrapings: Your doctor may scrape some scales off the rash and examine it (after treating it with drop of potassium hydroxide) under the microscope for fungus. In some cases the seborrhoea-like rash may be caused by a fungus and other skin infections. If fungus is the leadingcause of your skin problem then on examination under microscope fungal hyphae and its typical branching pattern may be seen.
Skin biopsy: This is a simple but invasive test in which a very small piece of skin is taken for examination under microscope. The sample of tissue is examined by a pathologis.This can help to diagnose the underlying pathology or disease. Some diseases of the skin which may cause symptoms similar to seborrheic dermatitis are: