Microcystic adnexal carcinomacancer arising from tissues that line organs (MAC), also known as a sclerosing sweat gland carcinoma or syringoid eccrine carcinoma, is a very rare type of cancera disease where abnormal cells split without control and spread to other nearby body tissue and/or organs that develops in the sweat glands of the body. It is most commonly found in the centre of the face, head, and neck, but can also be found in the trunk, limbs, breast, nipple, vulva, auditory (ear) canal, axillaarmpit, underarm, and perineumthe space between the scrotum and anus in males, and vaginal opening and anus in females. In very rare cases, it has also been found on the tongue, in the mouth, or in the maxillary sinus near the nose.
There are two primary types of sweat glands in the body: eccrine, and apocrine. Eccrine sweat glands are located all over the body, and open directly onto the surface of the skin. Their primary function is to assist the regulation of body temperature. Comparatively, apocrine sweat glands open into hair follicles, and generally develop in areas abundant in hair follicles (such as the scalp, armpits, and groinarea between the abdomen and thighs). Apocrine glands play no role in the regulation of body temperature, and are responsible for producing body odour. MAC can develop from both eccrine and apocrine sweat glands in the body.
MAC is generally considered to be a locally aggressive tumoura tissue mass that forms from groups of unhealthy cells, as it often infiltrates into surrounding tissuea group of cells that work together to perform a function, and generally has a high recurrenceto occur or happen again rate. However, metastasise (spread) to distant structures in the body is rare, it is often slow growing, and it often has a good prognosisto predict how a disease/condition may progress and what the outcome might be.
MAC is slightly more common in women, and tends to be diagnosed in people over 55 years old. However, anyone can develop this disease.
Treatment
If MAC is detected, it will be staged and graded based on size, metastasiswhen the cancer has spread to other parts of the body, also known as mets, and how the cancer cellsthe basic structural and functional unit of all living things look under the microscope. Stagingthe process of determining how big the cancer is, where it started and if it has spread to other areas 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 (nodea small lump or mass of tissue in your body) indicates whether the cancer has spread to nearby lymph nodessmall bean-shaped structures that filters harmful substances from lymph fluid.
- 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 had 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 localisedaffecting only one area of body 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 known as localised cancer.
- Stage IV: the cancer has spread to other tissues and organs in the body. This is also known as advancedat a late stage, far along or metastatic cancer.
Cancers can also be graded based on the rate of growth and how likely they are to spread:
- Gradea description of how abnormal cancer cells and tissue look under a microscope when compared to healthy cells 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 tumours. 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 testinga procedure that analyses DNA to identify changes in genes, chromosomes and proteins, which can be used to analyse tumour DNA to help determine which treatment has the greatest chance of success, which analyses your tumour DNA and can help determine which treatment has the greatest chance of success. They will then discuss the most appropriate treatment option for you.
Treatment is dependent on several factors, including location, stage of disease and overall health.
Treatment options for MACs may include:
- Surgerytreatment involving removal of cancerous tissue and/or tumours and a margin of healthy tissue around it to reduce recurrence, potentially including:
- Wide local excisionremoval of cancerous tissue and a margin of healthy tissue around it to prevent cancer recurrence.
- Mohs micrographic surgeryspecialised surgery that removes thin layers of cancer in stages until completely removed.
- Lymphadenectomysurgical removal of lymph node(s).
- Radiation therapya treatment that uses controlled doses of radiation to damage or kill cancer cells (limited).
- Chemotherapya cancer treatment that uses drugs to kill or slow the growth of cancer cells, while minimising damage to healthy cells (very limited).
- Clinical trialsresearch studies performed to test new treatments, tests or procedures and evaluate their effectiveness on various diseases.
- Palliative carea variety of practices and exercises used to provide pain relief and improve quality of life without curing the disease.
Risk factors
While the cause of MAC remains unknown, the following factors may increase the likelihood of developing the disease:
- Having pale skin.
- Prior exposure to ultraviolet (UV) radiation.
- Previous radiation therapy.
- Having a weakened immune system/immunosuppression.
Not everyone with these riskthe possibility that something bad will happen factors will develop the disease, and some people who have the disease may have none of these risk factors. See your general practitioner (GP) if you are concerned.
Symptoms
People with MAC may appear with vague and subtle symptoms in the early stages of disease. As such, MAC is often difficult to diagnose. People with MAC may experience:
- Coloured plaques on the skin:
- Patients with white or pale skin may notice a white, pink, or yellowish plaque.
- Patients with darker skin may notice a plaque or nodule with no pigmentary changes.
- Telangiectasiasmall, widened, red/purple blood vessels that are visible on the surface of the skin, also known as spider veins.
- Elevated nodule on the skin.
- Numbness and/or tingling in affected area.
- Pain in affected area.
- Burning and/or itchiness in affected area.
Not everyone with the symptoms above will have cancer, but see your general practitioner (GP) if you are concerned.
Diagnosis
If your doctor suspects you have a MAC, they may order the following tests to confirm the diagnosisthe process of identifying a disease based on signs and symptoms, patient history and medical test results and refer you to a specialist for treatment:
- Physical examinationan examination of your current symptoms, affected area(s) and overall medical history.
- Biopsyremoval of a section of tissue to analyse for cancer cells.
