Extramammary Paget disease (EMPD) is a rare type of skin cancer that generally affects areas with abundant sweat glands, such as anogenital (areas surrounding the anus and genitals) or axillary (the armpit area) skin. It is primarily an adenocarcinoma, which is cancer originating in glandular tissue. EMPD is different that mammary Paget disease, which has a similar appearance, but is found around the nipple and areola on the breast, and may be an indication of an underlying breast cancer.
EMPD can be classified into two categories, based on where the cancer originated from. The first is primary EMPD, which originates from the skin. The second category is secondary EMPD, which is associated with the metastasis of a primary adenocarcinoma originating somewhere else in the body.
EMPD is most commonly diagnosed in people over 50 and is more prevalent in females. However, this disease can be developed at any age in any gender.
Treatment
If EMPD is detected, it will be staged and graded based on size, metastasis and how the cancer cells look under the microscope. Staging and grading helps your doctors determine the best treatment for you.
Cancers can be staged using the TNM staging system:
- T (tumour) indicates the size and depth of the tumour.
- N (nodes) indicates whether the cancer has spread to nearby lymph nodes.
- M (metastasis) indicates whether the cancer has spread to other parts of the body.
This system can also be used in combination with a numerical value, from stage 0 – IV:
- Stage 0: this stage describes cancer cells in the place of origin (or ‘in situ’) that have not spread to nearby tissue.
- Stage I: cancer cells have begun to spread to nearby tissue. It is not deeply embedded into nearby tissue and has not spread to lymph nodes. This stage is also known as early-stage cancer.
- Stage II: cancer cells have grown deeper into nearby tissue. Lymph nodes may or may not be affected. This is also known as localised cancer.
- Stage III: the cancer has become larger and has grown deeper into nearby tissue. Lymph nodes are generally affected at this stage. This is also classified as localised cancer.
- Stage IV: the cancer has spread to other tissues and organs in the body. This is also known as advanced or metastatic cancer.
Cancers can also be graded based on the rate of growth and how likely they are to spread:
- Grade I: cancer cells present as slightly abnormal and are usually slow growing. This is also known as a low-grade tumour.
- Grade II: cancer cells present as abnormal and grow faster than grade I cancers. This is also known as an intermediate-grade tumour.
- Grade III: cancer cells present as very abnormal and grow quickly. This is also known as a high-grade tumour.
- Once your tumour has been staged and graded, your doctor may recommend genetic testing, which analyses your tumour DNA and can help determine which treatment has the greatest chance of success. They will then discuss the most appropriate course of treatment for you.
Treatment is dependent on several factors, including location, stage of disease and overall health.
Treatment options for EMPD may include:
- Surgery to remove as much of the tumour as possible. This may involve a Mohs Micrographic surgery, which removes portions of the cancer in stages.
- Radiation therapy.
- Chemotherapy.
- Clinical trials.
- Palliative care.
For more information on treatment options, please refer to the Rare Cancers Australia treatment options page.
Risk factors
Because of how rare EMPD is, there has been limited research into the risk factors of this disease.
Early symptoms
The symptoms of EMPD are often confused with other skin conditions, and as such is often misdiagnosed. The most common occurrence of EMPD is the vulva in women and on the scrotum or around the anus in men. Common symptoms of this disease are:
- Itchiness of the skin.
- Burning, pain, tenderness or irritation.
- Skin discolouration around the area.
- Crusting and/or scaling lesions of the skin.
- Weeping lesions of the skin.
Not everyone with the symptoms above will have cancer but see your general practitioner (GP) if you are concerned.
Diagnosis/diagnosing
Your doctor will usually start with a physical examination, followed by imaging tests to check for metastasis or underlying cancer. However, EMPD can only be diagnosed with a tissue sample (biopsy).
Imaging & blood tests
The doctor will take images of your body using magnetic resonance imaging (MRI), a computed tomography scan (CT scan), and/or positron emission tomography (PET scan), depending on where it is suspected the cancer is. The doctor may also look at other parts of the body and looks for signs of metastasis. Additionally, a blood test may be taken to assess your overall health and help guide treatment decisions.
Biopsy
Once the location(s) of the cancer has been identified, the doctor will perform a biopsy to remove a section of tissue using a needle. The tissue sample will then be analysed for cancer cells.
Prognosis (Certain factors affect the prognosis and treatment options)
While it is not possible to predict the exact course of the disease, your doctor may be able to give you a general idea based on stage, rate/depth of tumour growth, susceptibility to treatment, age, overall fitness and medical history. Generally, early-stage EMPD have good prognosis and survival rates. However, if the cancer is advanced and has spread, the prognosis may not be as good and there may be a higher risk of cancer recurrence.
References
Some references are to overseas websites. There may be references to drugs and clinical trials that are not available here in Australia.