In 2015 German researchers identified gene and signalling pathway differences between eczema and psoriasis. Many established treatments can be used for both conditions, but newer, more expensive condition-specific therapies are being introduced. With different disease processes involved in eczema and psoriasis, targeted therapy may be ineffective if the diagnosis is wrong. That’s why the researchers filed a patent for a test which could be used if a diagnosis could not be made when the patient presented.8,9

For most cases, though, diagnosis does rely on symptoms, history taking and appearance. NICE guidelines on assessing eczema are still “largely based on expert opinion” and says practitioners should examine all areas of affected skin, and ask about itching.10

Occasionally patients may also have both eczema and psoriasis at the same, or the appearance may not be clear cut resulting in a diagnosis of ‘psoriasiform’ dermatitis.

Doctors suspecting psoriasis can suggest a small biopsy procedure for examination under the microscope to rule out eczema. But for acute dermatitis, diagnosis usually relies on:3

·       the location and nature of the rash.

·       the extent of itching.

·       duration of symptoms and whether they come and go.

·       other atopic conditions such as asthma or hayfever.

·       the age at which the symptoms/rash first appeared.