Basal cell carcinoma is the most common type of skin cancer, starting in the basal cells at the bottom layer of your epidermis

Basal cell carcinoma (BCC) begins in the basal cells, which are round cells at the base of your outer skin layer. These cells constantly divide to replace the skin cells that flake away from the surface. When DNA damage in a basal cell prevents normal growth controls from working, the cell can divide uncontrollably and form a tumor.

BCC grows slowly and rarely spreads to other parts of your body, which is why it has a high survival rate. However, it can grow deeper into the skin and underlying tissue if left untreated, potentially causing disfigurement or damage to structures beneath the skin.

Most basal cell carcinomas appear on sun-exposed areas—the face, ears, scalp, neck, and hands. They account for roughly 80 percent of all skin cancers diagnosed in the United States, making them far more common than melanoma or squamous cell carcinoma.

Key Takeaways

  • Basal cell carcinoma starts in basal cells at the base of your epidermis and grows slowly, rarely spreading beyond the skin.
  • Ultraviolet (UV) radiation from the sun or tanning beds is the primary cause, with risk increasing after cumulative exposure over years.
  • Most basal cell carcinomas appear as a shiny bump, a sore that doesn't heal, or a scaly patch, usually on the face or other sun-exposed areas.
  • A dermatologist diagnoses BCC by removing a small sample of skin and examining it under a microscope.
  • Treatment options include surgical removal, freezing, topical creams, and radiation, depending on the tumor's size and location.

How UV radiation causes basal cell carcinoma

Ultraviolet light from the sun damages the DNA inside skin cells. Your skin has repair mechanisms that usually fix this damage, but repeated or intense UV exposure can overwhelm these systems. Over time, mutations accumulate in basal cells until one cell's growth controls fail entirely.

Both UVA and UVB rays contribute to this damage. UVB rays cause sunburns and are the primary culprit in most skin cancers. UVA rays penetrate deeper and cause cumulative damage that may not show as a burn. Tanning beds emit both types of UV radiation and carry the same risk as sun exposure.

The damage is cumulative—it builds up over a lifetime. You don't need a single severe sunburn to develop basal cell carcinoma. Years of regular sun exposure, even without obvious burns, can be enough. This is why BCC often appears in middle age or later, after decades of exposure.

Who is at higher risk

People with fair skin, light hair, and light eyes have less melanin, the pigment that absorbs UV radiation and protects cells from damage. This is why basal cell carcinoma is more common in people of European descent. However, anyone can develop BCC, including people with darker skin tones, though it typically appears later in life and in less sun-exposed areas.

Other factors increase risk: a personal or family history of skin cancer, a weakened immune system (from conditions like HIV or medications after organ transplant), exposure to arsenic or radiation for medical treatment, and certain genetic conditions like nevoid basal cell carcinoma syndrome, which causes multiple BCCs to develop.

Age matters too. BCC is rare before age 40 and becomes more common with each decade afterward. Men develop it more often than women, partly because of greater sun exposure from outdoor work or recreation.

What basal cell carcinoma looks like

Basal cell carcinoma appears in several forms. The most common is a shiny, pearly bump or nodule, often with a rolled edge and a depression or ulcer in the center. It may have visible blood vessels running across it. This type can look deceptively innocent—like a mole or a pimple that won't go away.

Another form is a sore that bleeds, oozes, or crusts over but never fully heals. It may appear and disappear, then return in the same spot. A third type looks like a scaly, flat patch of skin that may be red, brown, or skin-colored. This form can resemble eczema or psoriasis and is easy to miss.

Less common presentations include a waxy, scar-like area (morpheaform BCC) or a dark, crusty lesion that can resemble melanoma. Any skin growth that persists for more than a few weeks, especially one that bleeds or doesn't heal normally, warrants a visit to a dermatologist.

How dermatologists diagnose basal cell carcinoma

A dermatologist begins with a visual examination. If a lesion looks suspicious, they perform a biopsy—removing a small sample of skin under local anesthetic and sending it to a laboratory. A pathologist examines the sample under a microscope to confirm whether basal cells are growing abnormally and to determine the specific subtype of BCC.

The subtype matters for treatment planning. Nodular BCC (the most common form) is usually straightforward to treat. Infiltrative or morpheaform BCC grows with irregular borders and requires more careful removal to ensure all cancer cells are gone. Superficial BCC affects only the upper layers of skin and may respond to topical treatments.

Occasionally, a dermatologist may use dermoscopy—viewing the lesion under magnification with special lighting—to help decide whether a biopsy is needed. However, biopsy remains the only way to confirm the diagnosis.

Treatment options for basal cell carcinoma

Surgical excision is the most common treatment. The dermatologist removes the tumor along with a margin of normal-looking skin to ensure all cancer cells are gone. The wound is then closed with stitches. This approach works for most BCCs and allows the tissue to be examined under a microscope to confirm complete removal.

Mohs micrographic surgery is used for larger tumors, tumors in cosmetically sensitive areas (like the face), or BCCs that have recurred after previous treatment. The surgeon removes the tumor layer by layer, examining each layer under a microscope immediately, and stops only when no cancer cells remain. This technique removes the least amount of healthy tissue.

Cryotherapy freezes the tumor with liquid nitrogen, causing it to die and slough off. This works well for small, superficial BCCs but is less suitable for deeper tumors. Topical creams containing imiquimod or 5-fluorouracil can treat very superficial BCCs, though they require weeks of application and have higher recurrence rates than surgery.

Radiation therapy is an option for patients who cannot tolerate surgery or for tumors in difficult locations. Photodynamic therapy, which combines a light-sensitizing medication with a specific wavelength of light, treats some superficial BCCs. Your dermatologist will recommend the approach best suited to your tumor's size, depth, location, and your overall health.

Preventing basal cell carcinoma

Sun protection is the most effective prevention. Wear broad-spectrum sunscreen with SPF 30 or higher daily, even on cloudy days, because UV rays penetrate clouds. Reapply every two hours or after swimming. Wear protective clothing—long sleeves, pants, and wide-brimmed hats—especially during peak sun hours (10 a.m. to 4 p.m.).

Avoid tanning beds entirely. They emit concentrated UV radiation and increase skin cancer risk. If you have had basal cell carcinoma once, your risk of developing another is significant—roughly 40 percent of people develop a second BCC within five years. Regular skin self-exams and annual dermatology visits become especially important.

People at very high risk—those with a family history of melanoma, those who have had multiple BCCs, or those with genetic syndromes—may benefit from more frequent professional skin checks or preventive measures like retinoids, which some research suggests may reduce BCC risk, though this remains an emerging area.

Frequently Asked Questions

Can basal cell carcinoma spread to other parts of my body?

Basal cell carcinoma very rarely spreads to lymph nodes or distant organs. It grows locally into surrounding skin and tissue. However, if left untreated for years, it can become quite large and cause significant damage to the skin, underlying structures, or facial features. Early treatment prevents this.

Will I have a scar after basal cell carcinoma surgery?

Most surgical removal leaves a scar, though dermatologists use techniques to minimize it. The scar typically fades over months to years. Mohs surgery often results in smaller scars because less tissue is removed. Your dermatologist can discuss scar appearance and management options before treatment.

If I had basal cell carcinoma once, will I definitely get it again?

Not necessarily, but your risk is higher than the general population. About 40 percent of people who have had one BCC develop another within five years. Regular sun protection, self-exams, and annual dermatology visits reduce this risk and catch any new tumors early.

Does basal cell carcinoma run in families?

BCC itself is not strongly inherited, but the tendency to develop skin cancer can run in families. If your parents or siblings have had skin cancer, your risk is higher. Genetic syndromes like nevoid basal cell carcinoma syndrome do run in families and cause multiple BCCs, but this is rare.

How long does it take to treat basal cell carcinoma?

Surgical removal typically takes 30 minutes to an hour, though the appointment may be longer with preparation and closure. Mohs surgery takes longer—usually two to four hours—because of the layer-by-layer examination. Cryotherapy and topical treatments are quicker but may require multiple sessions over weeks.