Sebaceous carcinoma is a rare and aggressive skin cancer originating in the sebaceous glands. These glands produce the oily substance called sebum that lubricates the skin and hair. While sebaceous glands are found almost everywhere on the body, this cancer develops most frequently in the glands of the eyelids. It is also referred to as sebaceous gland carcinoma or meibomian gland carcinoma.
Symptoms and Common Locations
Sebaceous carcinoma presents as a firm, painless lump or nodule deep within the skin that tends to grow slowly. The growth is often yellowish or reddish and may bleed, ooze fluid, or form a crust. In some cases, a sore may appear that does not heal or that heals and then reappears.
Approximately 75% of these cancers occur in the ocular region, specifically on the eyelid. The upper eyelid is more commonly affected than the lower because it contains more meibomian glands, a specific type of sebaceous gland. An eyelid tumor might cause a thickening of the skin near the lash line, persistent reddish or crusty skin, or loss of eyelashes. Because its appearance can mimic common issues like a stye, chalazion, or conjunctivitis, diagnosis is often delayed.
Extraocular sebaceous carcinomas can develop anywhere on the body, though the head and neck are the second most frequent locations. Less commonly, these tumors appear on the trunk, genitals, ear canal, or breasts. In these locations, the carcinoma also presents as a slowly enlarging pink or yellowish lump that may bleed.
Causes and Associated Risk Factors
The precise cause of sebaceous carcinoma is not fully understood, but several factors increase the risk. Advanced age is a primary factor, with most people being diagnosed between 60 and 80 years old. A weakened immune system, resulting from conditions like HIV or from medications taken after an organ transplant, also elevates risk.
Previous exposure to radiation therapy, particularly to the head or neck area, is another established risk factor. While sun exposure’s role is less clear than for other skin cancers, many cases occur on sun-exposed areas. Some studies also suggest that individuals of Asian descent may have a higher risk.
A strong connection exists between this cancer and Muir-Torre syndrome, a rare inherited condition. This genetic disorder predisposes individuals to developing various sebaceous gland tumors and internal cancers, most commonly colorectal cancer. The appearance of a sebaceous carcinoma, especially in a person under 60 or in a location other than the eyelid, can be the first indication of this syndrome. This link means genetic evaluation should be considered when a sebaceous carcinoma is diagnosed.
The Diagnostic Process
Diagnosis begins with a physical examination of the skin lesion by a dermatologist or ophthalmologist. The doctor will inspect the growth, noting its size, shape, color, and texture. If the lesion is on the eyelid, the doctor will also check for signs that the cancer has spread to the surface of the eye.
The definitive diagnostic step is a skin biopsy, where a small sample of the suspicious tissue is removed for analysis. This may be an incisional biopsy, where only a part of the lesion is taken, or an excisional biopsy, where the entire growth is removed.
The tissue sample is sent to a pathologist who examines it under a microscope. The pathologist looks for characteristic features of sebaceous carcinoma, such as cells with a foamy appearance due to lipid content and patterns of invasive growth. This examination confirms the diagnosis and distinguishes it from other types of skin cancer or benign growths.
Available Treatment Modalities
The primary treatment for sebaceous carcinoma is surgical removal of the tumor. The surgical approach depends on the tumor’s size and location. Two main surgical techniques are used to ensure the complete removal of cancerous cells.
One preferred method, especially for tumors on the face and eyelids, is Mohs micrographic surgery. This procedure involves removing the tumor one thin layer at a time. After each layer is removed, it is immediately examined under a microscope to check for cancer cells at the margins, a process repeated until no cancer cells are detected. This technique maximizes the preservation of healthy surrounding tissue.
Another option is a wide local excision, where the surgeon removes the tumor along with a margin of normal-appearing tissue around it. This margin helps ensure that any cancer cells that may have spread into the adjacent skin are also removed. If the cancer has spread to nearby lymph nodes, surgery to remove those nodes may also be necessary.
Radiation therapy may be used as an additional treatment after surgery or if surgery is not a viable option. In advanced cases where the cancer has metastasized, systemic treatments such as chemotherapy might be considered.
Prognosis and Recurrence
The prognosis for sebaceous carcinoma is favorable when the cancer is detected and treated early. The survival rate for localized tumors that have not spread is over 90%, particularly if treatment occurs within six months of the first symptoms. A significant delay in diagnosis allows the tumor to grow larger or spread, which worsens the outcome.
This cancer has a known risk of recurrence and can return locally or metastasize to other parts of the body, most commonly the lymph nodes. Recurrence rates can vary, with some studies reporting that up to one in four people may experience a return of the cancer. The median time to a local recurrence is within the first two years following initial treatment.
Given the risk of recurrence and metastasis, regular long-term follow-up appointments are necessary. These check-ups allow a doctor to monitor the original site and check for any new or suspicious growths. Performing regular skin self-examinations is also encouraged to detect any changes as early as possible.