With any disease, an accurate diagnosis is the first step in ensuring proper treatment. A doctor makes the diagnosis of psoriasis after she or he has asked a series of questions and carefully examined your skin. In most cases, the physical examination of your skin alone is enough to make the diagnosis. There are a few things doctors will ask when making a diagnosis:
- Is there a family history of psoriasis?
- How long have you had this condition?
- What treatments have you received?
- How effective were they?
- Do you have tender and/or swollen joints (arthritis)?
- Are your fingernails/toenails affected?
- Do you have a history of skin lesions improving in summer and worsening in winter?
- Do you have one or more raised, red, silvery, scaling areas?
- Is the disease in the classic locations with symmetrical involvement of the elbows, knees, lower back, scalp, finger and/or toenails (rough, discolored appearance, often with individual pits in the nail plate)?
 |
| Diagnosis Of Psoriasis |
There are multiple types of psoriasis, and your doctor will examine you to see which type you have. Also, your doctor might want to see if other body areas are involved, such as the joints.
How Is Psoriasis Diagnosed?
Your doctor will analyze your skin, nails, and scalp in search of signs of psoriasis. The nails show changes in about 50 percent of all cases. There could be pitting, which looks like pinholes in the nail, and/or the nails may be yellowish or thickened, with ridges and scales heaped up at the free edge.
If there is still doubt whether psoriasis is present or not, the doctor could:
- perform a biopsy of the skin
- request X-rays, especially when joint pain is apparent
- take blood tests
Biopsy
A skin biopsy is used only in those instances when it is difficult to diagnose the disease. This relatively painless procedure involves numbing a small area of skin with a local anesthetic. A special instrument, called a "punch biopsy," is then rotated on the skin and light pressure applied, removing about a 1/8 inch (3-4 millimeter) piece of skin for testing. Following this procedure, one or two sutures might be used to stitch the skin, and a bandage applied.
The skin sample is then examined under a microscope. A pathologist - doctor specially trained to examine skin tissue under a microscope - will assist in examining the sample. Certain characteristics of the analyzed skin will help pathologists determine if psoriasis is the underlying cause.
X-rays
Where there is joint swelling or signs of joint deformity, X-rays can reveal characteristic damage to the joints. If there are signs of arthritis, the family doctor or dermatologist could request a rheumatologist - a specialist in arthritis - to examine the joints and assess the condition further.
Blood Tests
Blood tests may be performed if you have arthritis. A blood test called rheumatoid factor is commonly done to exclude rheumatoid arthritis. Rheumatoid factor is a protein found in the blood of most patients with rheumatoid arthritis. Most patients with psoriatic arthritis test negative for rheumatoid factor. Recently, it has become increasingly clear that psoriasis patients have an increased rate for a number of associated medical conditions, such as high blood pressure, diabetes, and obesity. As a result, your doctor may take your blood pressure, check your blood glucose, and perform a C-reactive protein test, which measures inflammation.
Distinguishing Psoriasis from Other Conditions
The diagnosis of psoriasis is usually straightforward. Still, several conditions can often be confused with psoriasis, eczema, and fungal (tinea) infections being the most common.
Eczema
Eczema differs from psoriasis in several ways.
- When eczema first appears, it is often wet and oozing. Psoriasis is usually dry with thick scales.
- Eczema is often very itchy, whereas psoriasis is often mildly itchy or not itchy at all. Some patients with psoriasis, however, can have itchy lesions.
- Cracks in the skin are often present in eczema.
- Patients with a hereditary form of eczema, called atopic eczema/dermatitis, often have a history of hay fever or asthma.
- Most cases of atopic eczema begin before two years of age, whereas most cases of psoriasis occur in adults.
- Eczema usually lacks the silver/scales of psoriasis.
- When eczema first appears, it is usually difficult to see a clear, well-defined border separating normal skin from eczema. In plaque psoriasis, there is a well-defined border that can usually be clearly distinguished from normal skin.
- Eczema may be confused with psoriasis, particularly if it has been present for several years.
- Hand or foot eczema may resemble psoriasis as the skin can be very thick.
- Eczema patients usually lack the nail changes seen in psoriasis patients.
Fungal Infections (Tinea)
- Fungal skin infections (commonly known as ringworm) are infections of the skin and nails that can resemble psoriasis.
- They may cause raised, red, scaly areas of the scalp (tinea capitis), body (tinea corporis), and hands or feet (tinea pedis).
- Fungal skin infections may also involve the nails.
These are several differences between psoriasis and fungal skin infections.
To establish a diagnosis, your doctor may take a scraping of the skin or clippings from the nail. These can be examined under a microscope, or cultured, and a diagnosis of fungus can be made, if positive.
 Diagnosis Of Posriasis |
| Diagnosis Of Psoriasis |
Candidiasis
- In the groin or under the breasts, candida infections (caused by yeast) may appear similar to inverse psoriasis.
- Taking a small scraping and examining the skin under the microscope can help distinguish psoriasis from candida infections.
To find out more, you can check out Diagnosis Of Psoriasis.