A carcinoma is a cancerous tumor of the epithelial tissue, which is the tissue underneath the skin. Basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) are the two most common types of skin cancer.

According to the estimates by the Skin Cancer Foundation, about 5.4 million people in the United States get carcinoma-type skin cancer each year.

Of those, annually, BCC accounts for about 3.6 million cases, and SCC accounts for 1.8 million cases, amounting to 67% and 33%, respectively.

The third most common skin cancer is melanoma, which is more dangerous than carcinoma, because it can spread quickly if doctors do not detect it early.

Carcinomas are more common than melanomas and more treatable. Estimates suggest that in 2022, melanoma is likely to affect only about 197,700 people in the U.S.

This article looks at the diagnosis and treatment of the two most common carcinoma cancers, as well as other types of carcinoma.

A carcinoma, also known as nonmelanoma skin cancer, is a cancerous tumor of the epithelial tissue, which is a protective tissue that covers surfaces throughout the body.

The skin, or the epidermis, is a type of epithelial tissue. BCC and SCC affect the epidermis.

The epithelial tissue is present not only under the skin but also everywhere in the body, including in the digestive tract, in blood vessels, and around many organs. This means that carcinomas can affect areas of the body other than the skin.

Healthcare professionals define the different carcinomas by the type of cell in which they occur.

BCC

BCC develops in basal cells, which are round skin cells that lie deep in the skin’s epidermis, below squamous cells. They form the base layer of the epidermis, which meets the dermis.

BCC is unlikely to spread, but doctors who suspect that an individual has this type of carcinoma will still refer them for further assessment.

BCC typically affects older adults, with a mean diagnosis age of 68 years.

SCC

Squamous cells make up most of the top layer of the epidermis. These cells are flat and scale-like.

SCC is the second most common skin cancer after BCC. It typically affects people after the age of 50 years.

Doctors who suspect SCC will provide a more urgent referral, as it is more likely to spread than BCC.

Other types of carcinoma

In addition to BCC and SCC, there are several other subtypes of carcinoma that affect the epithelial tissue other than the skin. They include:

Learn more about the types of carcinoma here.

BCC and SCC are both skin tumors, and they share some characteristics. However, these skin lesions can vary in appearance.

Some carcinomas retain a flat surface and, as a result, can resemble healthy skin. Anyone with any unexpected lesions should contact a healthcare professional for a checkup and monitoring.

Other than its presence, a lump or lesion often causes no noticeable symptoms in its early stages. As a result, it might not be noticeable until it becomes relatively large, when it may itch, bleed, or cause pain.

BCC

BCC typically presents as a shiny papule, which is a small red or pink lump that grows slowly. A shiny, pearly, or waxy-looking border may form after a few months or years.

A raised edge often rings a central ulcer, and unusually looking blood vessels might become visible. These may emerge as blue, brown, or black areas. Alternatively, they may be pink growths or pale or yellow areas that resemble scars.

Due to this wide range of appearances, obtaining an accurate diagnosis from a doctor is essential.

BCC might appear scaly, and it often causes recurrent crusting or bleeding. When it crusts over, it may resemble a healing scab, but sores can still appear. People with BCC often seek medical advice when they discover a sore that does not heal.

SCC

SCC typically presents as persistent, thick, rough, scaly patches or as a firm, pink lump with a flat, scaly, crusted surface.

These lesions may bleed if a person bumps, scratches, or scrapes them. While they sometimes resemble warts, they can also appear as open sores with a crusted surface or raised edge.

It is vital to seek the opinion of a healthcare professional regarding the development of any new growths or any changes in preexisting skin growths or sores.

The following images show what different carcinoma lesions can look like on the skin.

Exposure to UV radiation from sunlight is the primary cause of carcinoma and other skin cancers.

Some people are more sensitive to UV light and more vulnerable to the effects of sunlight on cancer development than others. Additional UV exposure from tanning beds and UV drying lamps in nail salons, for example, can add to a person’s risk.

UV radiation can cause damage to the DNA in skin cells, leading to mutations during cell division and possibly resulting in skin cancer.

Factors that increase the likelihood of carcinoma include a personal history of skin cancer and radiation treatment for any form of cancer, particularly in childhood. A family history of cancer may also play a role.

Other risk factors include:

SCC-specific risk factors

Actinic keratosis, which consists of rough, raised growths that cause precancerous changes in skin cells, is a risk factor specific to SCC.

These growths are the most common type of precancerous skin lesion. Without treatment, this condition may develop into skin cancer.

While UV radiation is the leading risk factor for SCC, the following skin damage can also increase the risk of this type of carcinoma:

  • burns to the skin
  • chemical damage
  • exposure to X-ray radiation

BCC might also develop after exposure to X-ray radiation in childhood, although this is a far less common cause of carcinoma than UV exposure.

Race and ethnicity

People who have a tendency to burn before getting a suntan, such as those who have light skin, can be more at risk of some types of carcinoma. This includes people with blue or green eyes and those who have blond, red, or light brown hair.

However, people with dark skin can also get skin cancer. According to a 2016 study, SCC comprises 30–65% of skin cancer cases among people with dark skin, compared with 15–25% among white people.

BCC is more common among people who are white, comprising about 65–75% of skin cancer cases in this group, compared with 20–30% among People of Color.

Moreover, BCC is more prevalent among Latino, Chinese, and Japanese populations than it is among African Americans and Asian Indians.

In many cases, people with dark skin receive a skin cancer diagnosis much later, when the condition is more life threatening.

Learn more about skin cancer on Black skin here.

To diagnose any form of skin cancer, a doctor will carry out a physical examination. They will examine the skin lesion and record its size, shape, texture, and other physical attributes.

They may also take a photo of the lesion for specialist review or to record its current size and appearance for future comparisons. The doctor will often check the rest of the body for additional skin symptoms.

They will also take a medical history focusing on the lesion and any related conditions, such as sunburn.

A doctor will urgently refer suspected cases of SCC for specialist investigation and treatment due to their tendency to spread. Suspected BCC tumors do not require such urgent referral, as they are less likely to spread.

If the doctor thinks that a lesion may be cancerous, they are also likely to perform a biopsy. There are four different types of skin biopsy, all of which involve the removal of skin tissue for laboratory assessment.

The different types are:

  • Shave biopsy: Using a sharp surgical blade, the doctor shaves the top layers of skin cells, usually as far as the dermis but sometimes deeper. This type of biopsy often results in bleeding, but it is possible to stop this by cauterizing the wound, meaning sealing it using heat.
  • Punch biopsy: The doctor uses a sharp, hollow surgical tool that resembles a tiny cookie cutter to remove a circle of skin from below the dermis. A person may need a single stitch to close the resulting wound.
  • Incisional biopsy: The doctor removes part of the growth with a scalpel, cutting away a full-thickness wedge or slice of skin. This type of biopsy often needs more than one stitch afterward.
  • Excisional biopsy: The doctor removes the whole growth and some surrounding tissue with a scalpel. The resulting wound usually requires stitches.

After taking the tissue sample, the doctor will send it to a pathology laboratory for examination under a microscope. The pathology team will assess the cells to look for cancerous traits. If cancer is present, the pathologists will determine its type.

The American Academy of Dermatology (AAD) recommends removing BCC lesions. While these lesions rarely spread, they can grow and become disfiguring and dangerous, depending on their location. The lesions can grow deep into the skin and affect the bones. In rare cases, BCC does spread aggressively.

Individuals with SCC may need to undergo tests for cancer in other tissues.

Additional tests usually involve imaging and may include:

Treatment options for both types of carcinoma are similar, although the medical team will place greater emphasis on monitoring people with SCC for signs of metastasis.

The specific treatment or treatments that a doctor recommends will depend on the size, type, stage, and location of the carcinoma. The doctor will also take into account other factors, such as potential side effects and a person’s preferences.

Either way, treatment is likely to involve a team of healthcare professionals, including dermatologists and surgical, medical, and radiological cancer specialists.

Treatment options may include surgical, chemical, and alternative modalities.

Surgery

Surgical options to treat carcinomas include:

  • Curettage and electrodesiccation: This is a standard procedure for removing a small lesion. The doctor uses a small, sharp, spoon- or ring-shaped instrument called a curette to scrape away the carcinoma before burning the site with an electric needle. It may take more than one round of curettage and desiccation to remove the cancer cells entirely.
  • Surgical excision: A surgeon removes the lesion, sometimes in a procedure known as Mohs surgery, which works better on larger lesions. During this procedure, the surgeon checks for the presence of cancer cells after removing each layer. Mohs surgery is particularly useful in cases that require the removal of as little skin as possible, such as on lesions near the eye. Doctors will also use it on lesions with a high risk of recurrence.
  • Cryosurgery: For small tumors, doctors might use this procedure, which involves applying liquid nitrogen to freeze and kill cancer cells. The lesion then blisters over and falls off in the weeks following treatment.

Chemotherapy and medication

These treatments include:

  • Topical chemotherapy: The doctor may prescribe that a person apply chemicals or medications that kill cancer cells directly to the skin. The chemotherapy option is 5-fluorouracil, which includes Carac, Efudex, Fluoroplex, and other medications. The doctor can apply this cancer-killing drug to the skin once or twice daily for several weeks. As this local treatment does not reach other systems in the body, it does not cause the side effects that often occur with chemotherapy for other types of cancer.
  • Imiquimod cream: This cream is available under the brand names Aldara and Zyclara. It is an immune response modifier that is sufficient for treating small BCCs. It works by encouraging the body to produce interferon, which causes the immune system to attack the tumor.
  • Interferon: This is a naturally occurring protein that the immune system releases to fight an invading organism, such as a virus. Doctors can also give a person interferon to treat a variety of health conditions. A doctor might inject interferon directly into a carcinoma lesion.

Other treatment options

Other treatments for carcinomas include:

  • Radiation therapy: The treatment team can target large or difficult-to-remove lesions with focused radiation.
  • Photodynamic therapy: Doctors will sometimes use this two-step therapy to treat BCC. They will apply a light-sensitive cream to the affected area of the skin and then expose it to a powerful light source. The light has a particular wavelength of blue light, which leads to the death of carcinoma cells. As the skin remains sensitive to light for the next 48 hours, people should avoid UV light during this time to minimize the risk of severe sunburn.
  • Laser therapy: This involves the use of different types of lasers to destroy cancer cells. Some lasers vaporize, or ablate, the skin’s top layer, destroying any lesions that are present there. Other lasers are non-ablative and penetrate the skin without removing the top layer. There is some evidence of their success in treating small, superficial BCCs. The Food and Drug Administration (FDA) has not yet approved laser therapy for BCC. However, doctors may sometimes use it as a secondary therapy if other treatments have not been successful.

Treatment for carcinoma is likely to be more effective in cases where a person identifies skin changes at an early stage and receives prompt medical attention.

In cases where cancer is responsible for skin changes, early treatment considerably improves the chance of survival and reduces the likelihood of significant tissue trauma and disfigurement.

BCC has an excellent survival rate, as it very rarely spreads beyond the original site. Doctors can often treat it in-office.

Although SCC is more likely to spread, it is treatable in its early stages. Most treatments are over 95% effective.

However, if SCC spreads beyond the original site and reaches other systems in the body, it becomes much more life threatening. At this point, less than half of people who receive a diagnosis will likely die even with aggressive treatment.

Early identification is essential to improving a person’s outlook.

Below, we answer some common questions about carcinoma.

How can I prevent carcinoma?

The main risk factor for both types of carcinoma is UV light.

The best prevention strategy is to protect the skin from the sun. This includes staying in the shade during peak sun hours, wearing a hat and sunglasses, and using a broad-spectrum sunscreen with an SPF of 15 or higher.

A person should also avoid using tanning beds, tanning parlors, and sunlamps. Additionally, people should regularly examine their skin.

How do I look for carcinoma on the skin?

Generally, a person should look for changes in size, shape, color, or texture anywhere on their skin.

People with dark skin may find it harder to notice signs of skin cancer. The AAD recommends they look for dark spots that grow, bleed, or seem to change, sores that do not heal, a dry or rough patch of skin, or a dark line underneath or around a fingernail or toenail.

How do doctors determine the carcinoma cancer stage?

To determine the cancer stage, a doctor will assess the size and depth of the carcinoma lesion and the extent to which it has spread to local and distant sites in the body, such as nearby lymph nodes or other organs.

The doctor may also take tissue from lymph nodes near the site of the carcinoma and use a fine-needle biopsy for laboratory examination.

Is carcinoma always malignant?

Carcinoma is malignant cancer that begins in the skin or the tissues that line the organs inside the body.

What is the difference between carcinoma and sarcoma?

Sarcoma is cancer that begins in the bones or connective tissues inside the body. This can also include the blood vessels, nerves, or muscles.