Extramammary Paget’s Disease

Extramammary Paget’s disease (EMPD) is a rare skin condition that causes a red, scaly and itchy rash. Usually, it’s on the skin on or around your genitals and anus. It grows slowly and can look like common skin conditions, like eczema. This can delay diagnosis. Often, EMPD isn’t diagnosed until many months or even years after it starts.

But preventing delays is important because this condition can be serious. Up to 1 in 5 people with extramammary Paget’s disease have an underlying cancer. EMPD isn’t always a sign of another disease, though. 

Getting treatment can help improve your symptoms. It’s also important to see a healthcare provider so they can check for cancers that may be linked to the disease.

Types of extramammary Paget’s disease

There are two types of EMPD:

• Primary: This type is more common. It happens when abnormal cells — called Paget cells — form in your skin.
• Secondary: With the secondary type, the skin changes are a sign of cancer inside your body.

The skin changes look the same in both types. This is why checking for an underlying cancer is an important part of an EMPD diagnosis.

Symptoms of extramammary Paget’s disease

The main symptom of EMPD is a red, scaly or crusty skin rash that looks like eczema. EMPD most often appears where you have lots of sweat glands that open into hair follicles. These are called apocrine glands. The most common site is your genitals (vulva, penis or anus). It can also appear on skin in other places with lots of these glands, like your armpit.

In about 1 in 10 people, the skin changes are the only sign of EMPD. But in most people, the skin feels:

• Itchy
• Burning or irritated
• Painful, tender or swollen

The rash grows slowly and may have irregular borders. As the disease progresses, deep sores called ulcers or nodules may form.

Extramammary Paget’s disease causes

Healthcare providers don’t know the exact cause. But they suspect that primary EMPD forms from certain types of skin cells, like:

• Apocrine gland duct cells: Sweat glands in your skin related to hair follicles
• Keratinocyte stem cells: Cells that help with skin repair
• Toker cells: Cells in the skin of the nipple and vulva 

Secondary extramammary Paget’s disease results from a cancer inside your body. Types that may cause secondary EMPD include:

• Anal cancer
• Bladder cancer
• Cervical cancer
• Ovarian cancer
• Prostate cancer
• Rectal cancer
• Uterine cancer

Risk factors

Anyone can develop extramammary Paget’s disease. But the risk is greater if you are:

• Between 50 and 80 years old
• Female and white (in Western countries, like the United States)
• Male (in Eastern countries, like China)

Experts don’t know why males are more at risk in Asia while females are more at risk in the U.S.

Complications of this condition

It’s rare for extramammary Paget’s disease to spread throughout your body. But it may sometimes progress to lymph nodes or other organs. Sometimes, internal cancers arise after a diagnosis of primary EMPD. When this happens, it usually takes place within the first five years of a diagnosis.

This is why your healthcare provider will monitor you closely if you have EMPD.

How doctors diagnose this condition

A healthcare provider will ask about your symptoms and do a physical exam. It’s easy to mistake EMPD for more common skin conditions that also cause rashes. Often, diagnosis happens when the rash remains after treatments for another skin issue.

To diagnose EMPD, your provider will do a skin biopsy. They’ll check for a type of cell called a Paget cell to confirm the condition. They’ll also see how Paget cells react to various chemicals (immunohistochemistry) to correctly identify these cells.

You’ll need more tests to see if extramammary Paget’s disease is related to an underlying cancer. Tests may include:

• Colonoscopy
• Digital rectal exam
• Mammogram
• Pap smear
• Prostate-specific antigen (PSA) test
• Urine cytology

You may need other tests based on your symptoms and the location of skin changes.

How is extramammary Paget’s disease treated?

The first-line treatment for EMPD is surgery. This means it’s the main treatment healthcare providers use. Methods include:

• Mohs surgery: Your surgeon removes the affected skin cells layer by layer. This technique helps save the surrounding healthy skin.
• Wide local excision: Your surgeon removes the abnormal areas, along with some healthy tissue around it. This is to ensure that no microscopic disease remains. 

Your provider may suggest the following treatments if you can’t have surgery safely:

• Immunotherapy
• Laser skin resurfacing
• Photodynamic therapy (PDT)
• Radiation therapy
• Skin creams, like imiquimod and 5-fluorouracil

It’s also possible to need these treatments in addition to surgery or if EMPD comes back (recurs) after surgery.

Any underlying cancers will need additional treatment.

When should I see my healthcare provider?

After treatment, you’ll need ongoing visits with your provider to get skin exams. You may also need imaging and other tests. It’s essential that you’re up to date on all recommended cancer screenings.

It’s not uncommon for EMPD to come back in the same area that was already treated, or in the surrounding area. So, follow-up is important. In some cases, EMPD can return after more than 15 years.

Your provider will discuss your follow-up timeline with you.

What can I expect if I have extramammary Paget’s disease?

Your outlook depends on lots of factors that vary from person to person. In general, EMPD that’s only in the surface layers of your skin has a better outlook than disease that extends into deeper layers. The outlook is better with EMPD that doesn’t involve an underlying cancer.

Other factors can also influence your outcome. Your healthcare provider is the best person to explain what’s most likely in your case.

What is the difference between extramammary Paget’s disease and Paget’s disease of the breast?

The skin changes are mostly the same. The difference has to do with location. Like the name suggests, Paget’s disease of the breast is in your breast. Extramammary Paget’s disease is in places other than your breast.

Both conditions are named for Sir James Paget, a famous 19th century British pathologist. Many forms of cancer carry his name because of his work identifying diseases. This is why providers look for “Paget” cells when making a diagnosis.

Is extramammary Paget’s disease a cancer?

It varies. The skin changes in EMPD happen because of abnormal cells. Sometimes, the cells are cancerous or precancerous. But they don’t always behave the same. In some people, the cells are only in the top layers of skin, where healthcare providers can easily remove them. This can cure EMPD in some cases. Other times, the cells invade tissue and are hard to get rid of completely.

Your healthcare provider will explain whether cancer is a part of your diagnosis.