No special blood test or other diagnostic tool exists for psoriasis. The diagnosis is usually determined through examination of the skin by a physician or other health care provider. Less commonly, a skin biopsy is examined under the microscope for biological evidence of psoriasis. The presence of small pits in the fingernails is also an indicator of psoriasis. There are various forms of psoriasis.
Plaque psoriasis is the most common.
No, psoriasis is not contagious. Lesions of psoriasis may be unsightly, but they should not be regarded as an infection or an open wound. An individual with psoriasis poses no threat to the health or safety of others. Psoriasis most commonly appears on the scalp, knees, elbows and torso. Often the lesions appear in a symmetrical fashion, in the same place on the right and left sides of the body.