Sebaceous carcinomas are rare and aggressive carcinomas (cancera disease where abnormal cells split without control and spread to other nearby body tissue and/or organs arising from tissues that line organs) that affect develop in the skin. More specifically, they develop in sebaceous glands attached to hair follicles in the skin. These glands produce the natural oils in the skin, mainly a substance called sebum. Sebum is a group of complex oils that lubricates the skin in order to protect the skin from friction, as well as acting as a waterproofing mechanism.
Sebaceous carcinomas are more common in women, and are generally diagnosed in people over 60 years old. However, anyone can develop this disease.
Types of Sebaceous Carcinomas
There are two primary types of sebaceous carcinomas, which are categorised by the areas of the body that they develop from.
Periocular Sebaceous Carcinomas
Periocular sebaceous carcinomas are the most common subtype of sebaceous carcinomas, and are generally found around the eyes. More specifically, they develop in the meibomian glands in the eyelids, which are responsible for secreting the lipid layer that prevents tears from drying out on the ocular surface. While this type of cancer can be aggressive, it can have a good prognosisto predict how a disease/condition may progress and what the outcome might be when caught early.
Extraocular Sebaceous Carcinomas
Extraocular sebaceous carcinomas are less common, and develop outside of the eye area. Generally, they can be found in the head and neck, but they have also been found in other areas such as the genitals, ear canal, breasts, trunk, and oral cavity. While this type of cancer can be aggressive, it can have a good prognosis when caught early.
Treatment
If sebaceous carcinomacancer arising from tissues that line organs 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 (tumoura tissue mass that forms from groups of unhealthy cells) 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 tissuea group of cells that work together to perform a function.
- 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 sebaceous carcinomas may include:
- Surgerytreatment involving removal of cancerous tissue and/or tumours and a margin of healthy tissue around it to reduce recurrence, potentially including:
- Mohs micrographic surgeryspecialised surgery that removes thin layers of cancer in stages until completely removed.
- Wide local excisionremoval of cancerous tissue and a margin of healthy tissue around it to prevent cancer recurrence.
- Lymphadenectomysurgical removal of lymph node(s).
- Enucleationremoval of the eye and attached optic nerve (only in rare and extreme cases).
- Radiation therapya treatment that uses controlled doses of radiation to damage or kill cancer cells.
- 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 sebaceous carcinomas remains unknown, the following factors may increase the riskthe possibility that something bad will happen of developing the disease:
- Having non-cancerous lumps (also known as benignnot cancerous, can grow but will not spread to other body parts adenomas) in the sebaceous glands.
- Prior exposure to radiation.
- Having certain conditions, such as:
- Muir Torré syndrome.
- Lynch syndrome.
- Being immunocompromised.
- Prior history of oral thiazide diuretic use.
- Genetic mutations to the p53 tumour suppressor gene.
Not everyone with these risk 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
The symptoms of sebaceous carcinomas often vary by subtype.
Symptoms of Periocular Sebaceous Carcinomas
Symptoms of periocular sebaceous carcinomas may include:
- Painless, rounded nodule on the eyelid.
- Inflammation and/or pain in the affected area.
- Red or yellowish nodule.
- Nodule that oozes bloodthe red bodily fluid that transports oxygen and other nutrients around the body.
Symptoms of Extraocular Sebaceous Carcinomas
Symptoms of extraocular sebaceous carcinomas may include:
- Yellowish-tan coloured nodule.
- Ulcerated nodule.
Not everyone with the symptoms above will have cancer, but see your GP if you are concerned.
Diagnosis
If your doctor suspects you have a sebaceous carcinoma, 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.
- Eye tests, potentially including:
- Ophthalmoscopyan examination of the back of the eye (fundus) to visualise the retina, optic disc and/or blood vessels; also known as a fundoscopy.
- Fluorescein angiographyan eye test that involves using a special dye and camera to examine blood flow in the retina and choroid.
- Electroretinographyan eye test that measures small electrical signals given off by the eye when exposed to different types of light.
- Biopsyremoval of a section of tissue to analyse for cancer cells.
