Psoriasis is generally diagnosed through a physical examination. If a physical exam isn’t sufficient to diagnose psoriasis, a dermatologist may order a procedure known as a skin biopsy.

Psoriasis is a chronic skin condition that causes inflammation and the accelerated production of skin cells. It’s important to seek a diagnosis from a health care professional if you suspect that you may have psoriasis. Psoriasis symptoms can be confused with those of other conditions, such as eczema. For this reason, psoriasis is most commonly diagnosed by a dermatologist — a doctor specializing in conditions of the skin, hair, and nails. They may rule out the possibility of other conditions and determine whether psoriasis is causing your symptoms.

What Is a Skin Biopsy?

A skin biopsy is a procedure that involves removing a small skin sample for testing. Doctors examine this skin sample under a microscope to check for signs of skin diseases or conditions like psoriasis. Standard skin biopsies can be performed in a dermatologist’s office or another outpatient health care facility.

There are three main types of skin biopsies: shave biopsy, excisional biopsy, and punch biopsy.

Shave Biopsy

During a shave biopsy, a doctor uses a tool similar to a razor blade to remove a small section of the top layers of skin (the epidermis and a portion of the dermis). This procedure is commonly done to look for skin cancers that are in the top layers of the skin.

Excisional Biopsy

An excisional biopsy involves using a small knife known as a scalpel to remove an abnormal area of skin, as well as a portion of normal skin. Excisional biopsy goes down to or through the fatty layer of skin. This procedure is usually done when a dangerous type of cancer is highly suspected.

Punch Biopsy

A punch biopsy is most commonly used to diagnose psoriasis. A punch biopsy involves using a circular tool to remove a small section of deeper layers of skin (the epidermis, dermis, and superficial fat). A circular piece of skin with a 3 millimeter diameter is commonly biopsied by the punch method.

What To Expect During a Punch Biopsy

The name punch biopsy refers to the technique used to remove the skin sample. During a punch biopsy, the skin is usually numbed by injecting anesthetic into the skin. The doctor uses a device similar in size and shape to a pencil to puncture the skin. One or two stitches may be required to close the wound after the skin sample has been removed.

The biopsy typically takes about five minutes from start to finish, including the time it takes to prepare, dress the wound, and provide instructions for home care. After the biopsy, your skin sample will be sent to a laboratory for examination. The results of a skin biopsy should be ready in about one week.

What Else Is Involved in Diagnosing Psoriasis?

There are five main types of skin psoriasis. During diagnosis, your doctor may assess your signs and symptoms to diagnose you with one of the following:

• Plaque psoriasis (the most common type of psoriasis)
• Guttate psoriasis
• Inverse psoriasis
• Pustular psoriasis
• Erythrodermic psoriasis

Doctors identify which type of psoriasis a person has by their symptoms. Learn more about the types of psoriasis.

Psoriasis is generally diagnosed clinically. Clinical diagnosis is based on a person’s medical history, signs, symptoms, and a physical exam. In most cases, a dermatologist can diagnose psoriasis with an examination alone. A skin biopsy may be required if a dermatologist needs more information to rule out other potential causes of your symptoms, such as skin conditions that may resemble psoriasis.

During a physical exam, a dermatologist will examine the skin, taking note of any red or purple, flaky, dry patches of skin (plaques). They will likely observe the size, location, and shape of these plaques, as well as where they are located on your body. A dermatologist may also ask about any joint symptoms and examine your nails for signs of pitting, ridges, or separation from the nail bed, all of which are indicators of psoriatic arthritis (PsA).

Let your doctor know if you are taking any medications or have any other health conditions. Some conditions, including HIV/AIDS, may weaken the immune system, increasing a person’s risk of psoriasis.

It Takes a Team

Living with a chronic health condition like psoriasis can be a challenge. The good news is that you don’t have to do it alone.

MyPsoriasisTeam is the social network for people with psoriasis and psoriatic arthritis and their loved ones. On MyPsoriasisTeam, more than 88,000 members come together to ask and answer questions, offer support, and share their stories of everyday life with psoriasis and PsA. Members frequently talk about what it was like to be diagnosed with psoriasis.

Did you need a skin biopsy to be diagnosed with psoriasis? Share your experience with others in the comments below, or make a new post on MyPsoriasisTeam.