What are sebaceous glands?

Sebaceous glands are small glands found in the skin that produce sebum, an oily substance that helps keep the skin and hair soft, flexible, and protected. These glands are distributed throughout the body but are most numerous on the face, scalp, upper chest, and back. Sebaceous glands are connected to hair follicles, and the sebum they produce travels along the hair shaft to reach the surface of the skin.

Sebaceous glands begin working during puberty under the influence of hormones, which is why oiliness and acne often increase during the teenage years.

What does a sebaceous gland do?

The primary function of a sebaceous gland is to produce sebum. Sebum has several vital roles:

• It protects the skin by forming a thin barrier that helps prevent dryness.

• It lubricates hair, making it less likely to break.

• It has antimicrobial properties, meaning it can help protect the skin from certain bacteria and fungi.

Healthy sebum production supports normal skin function and helps maintain the skin’s natural moisture barrier.

Where are sebaceous glands normally found?

Sebaceous glands are found in almost all areas of the skin except for the palms of the hands and the soles of the feet. They are usually attached to hair follicles, although in some areas—such as the eyelids (Meibomian glands) and lips (Fordyce glands)—they can be found on their own.

Because sebaceous glands are present in most skin, they may be seen in biopsies taken for many different dermatologic conditions.

What do sebaceous glands look like under the microscope?

Under the microscope, sebaceous glands appear as clusters of round or grape-like cells located next to a hair follicle. These cells contain tiny oil droplets, making their cytoplasm (the cell’s body) appear pale or foamy. As the cells mature, they fill with more oil and eventually break down, releasing sebum into the hair follicle.

Pathologists can recognize sebaceous glands by their distinctive appearance and close association with hair follicles.

What conditions are associated with sebaceous glands?

Several common and uncommon skin conditions involve sebaceous glands:

Acne

Acne occurs when hair follicles and sebaceous glands become clogged with oil and dead skin cells. This can lead to inflammation, blackheads, whiteheads, and pimples.

Sebaceous hyperplasia

Sebaceous hyperplasia is a benign condition in which sebaceous glands become enlarged. It often appears as small, soft bumps on the face, especially in older adults.

Sebaceous adenoma and sebaceoma

These are benign tumours made from sebaceous gland cells. They usually appear as slow-growing bumps on the skin.

Sebaceous carcinoma

Sebaceous carcinoma is a rare but aggressive cancer that begins in sebaceous gland cells. It most commonly affects the eyelids, but can occur anywhere sebaceous glands are found. Early diagnosis is essential because this tumour can spread if not treated promptly.

Genetic conditions

Some inherited syndromes, such as Muir–Torre syndrome, are associated with sebaceous tumours. When a sebaceous tumour is found, your doctor may recommend additional testing depending on your medical and family history.

Why are sebaceous glands mentioned in my pathology report?

Sebaceous glands may appear in your pathology report for several reasons:

• They may be completely normal and simply part of the tissue sample.

• They may show inflammation, enlargement, or blockage in conditions such as acne or dermatitis.

• They may be part of a benign tumour such as sebaceous hyperplasia or sebaceoma.

• They may be part of a malignant tumour, such as sebaceous carcinoma.

The presence, absence, or appearance of sebaceous glands helps the pathologist understand what is happening in the tissue and contributes to the final diagnosis.

Questions to ask your doctor

• Why were sebaceous glands mentioned in my pathology report?

• Were the sebaceous glands normal, or did they show signs of inflammation or tumour growth?

• Do the findings suggest a benign condition or something requiring further investigation?

• If a sebaceous tumour was found, do I need additional testing for hereditary conditions?

• What treatment or follow-up is recommended based on these results?