Skin Biopsy and How It Can Help Diagnose aHUS

Emily Malcolm, PhD avatar

by Emily Malcolm, PhD |

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A skin biopsy is one of the tests that doctors can use to confirm a diagnosis of atypical hemolytic uremic syndrome (aHUS), a rare disease characterized by blood clotting in the small blood vessels of the kidneys that can damage these organs.

The kidneys play an essential role in filtering wastes from the blood. When they cannot function properly, these wastes can build in the blood to dangerous levels.

What is a skin biopsy?

A skin biopsy is a procedure in which doctors remove a small piece of skin for testing. There are three main ways that they can do this: shave, punch, and excision.

In a shave biopsy, a tool similar to a razor is used to remove or “shave” a small sample of the top few layers of skin. To perform a punch biopsy, the doctor uses a device like a thick syringe to remove a small piece of skin (usually 1 to 2 mm in diameter). An excisional biopsy uses a small scalpel to remove a small piece of skin.

The skin samples can be examined under a microscope for abnormalities. They can also be used for genetic testing, among other potential tests.

How do doctors use skin biopsies to diagnose aHUS?

aHUS is caused by abnormalities in a portion of the immune system called the complement system. The complement system normally acts to enhance the effectiveness of the immune system in responding to threats. When an antibody recognizes a bacterium or a virus-infected cell, for example, the complement system helps call immune cells to the infection site. In aHUS, however, the complement system becomes active without the presence of an infection. This causes small blood clots, and the destruction of platelets and red blood cells.

Doctors can use skin biopsies to look at the small blood vessels in the skin under a microscope. Many patients with aHUS show abnormalities in their skin. Small blood clots and accumulated complement proteins in the blood vessels of the skin are present in most patients.

These features can disappear following treatment. Doctors therefore may also request a skin biopsy to determine whether a treatment is working.

How to prepare?

If your doctor orders a skin biopsy, a few preparatory steps are usually necessary. You should tell your doctor if you have any history of bleeding disorders, skin infections, or if you are taking any medications that suppress your immune system, as your doctor may need to take additional precautions during the procedure.

Your doctor will use a numbing agent (a local topical anesthetic) on the area of skin to be biopsied. Following an excisional or punch biopsy, you may need one or two stitches to close the site, though this is rare. The doctor will bandage the biopsy site and discuss further care of the site with you, and warning signs of an infection. If you notice bleeding, redness, or streaking of the skin near the biopsy site, you should contact your doctor immediately.

What are the risks?

Skin biopsies are generally a low-risk procedure, however, there are potential complications that you should discuss with your doctor in advance. As with any skin injury, there are risks of infection and bleeding. Depending on the type of biopsy, there may be some scarring at the biopsy site.

What happens after the skin biopsy?

After the biopsy, the doctor will bandage the area and may give you a pain reliever, like acetaminophen. Your doctor will send the biopsy sample out for testing. It may take a few days to a few weeks for the results to come back. Your doctor will then meet with you to discuss the results and treatment options.


Last updated: June 22, 2020


AHUS News is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.