What you need to know about the kind of skin cancer US first lady Jill Biden was treated for

The skin cancer first lady Jill Biden was treated for Wednesday - basal cell carcinoma - is highly treatable and the most common form of skin cancer, experts said.

Doctors removed lesions from above Biden's right eye and the left part of her chest using Mohs surgery, a common procedure for that type of skin cancer, according to the White House. A third lesion, on her left eyelid, was surgically excised and sent to a lab for examination.

What are the most common skin cancers?

Basal cell and squamous cell cancers are the two most common types. Combined, the two cancers are diagnosed in more than 3.3 million Americans each year. They appear in areas exposed to the sun, such as the face, head and neck, according to the American Cancer Society.

Basal cell cancers tends to grow extremely slowly and are very unlikely to spread, doctors said. They can appear as an unusual growth on the skin.

"You may notice a waxy lump or a small, smooth, shiny, or pale growth," according to the website of Memorial Sloan Kettering Cancer Center in New York. "Or there may not be a lump at all, but instead you notice a flat spot that looks slightly different from the rest of your skin."

Only about 2,000 Americans die each year from basal cell and squamous cell cancers.

Melanoma, which is much less common, is more dangerous because it is more likely to spread to other parts of the body. The key is catching melanoma early and treating it right away, the cancer society said. Doctors urge anyone suspecting melanoma to see a specialist right away.

What is basal cell carcinoma?

This cancer is caused by a mutation to the genetic material in basal cells, which are found at the bottom of our outer most layer of skin. Healthy basal cells produce new skin cells and simultaneously push older cells to the skin surface where they die and are shed from the body. The cancer can be caused by ultraviolet radiation from sunlight or commercial tanning lamps.

The risk of basal cell carcinoma is higher in people who have fair skin, red or blond hair or light-colored eyes, according to Mayo Clinic. Most of the lesions occur in people who are older than 50.

What is the treatment for basal cell carcinoma?

One of the most common treatments is Mohs surgery, an outpatient procedure that Biden underwent Wednesday at Walter Reed National Military Medical Center.

Basia M. Michalski, assistant professor of dermatology at Washington University in St Louis, said the procedure is designed to completely remove the cancer while sparing as much healthy tissue as possible.

The patient typically remains awake during the procedure but is given one medication to numb the affected area and another to reduce possible bleeding.

After the numbing agent takes affect, the surgeon removes a thin layer of skin and takes it to the lab for examination under a microscope.

"I continue that procedure until I as a surgeon don't see any more cancer," Michalski said. "If we take one layer and everything looks good under the microscope, we don't have to go back for more."

Jenny Kim, a dermatologist at UCLA Health, echoed Michalski, saying that the cure rate when basal cell carcinomas are removed with Mohs is 99 percent.

"It's very highly treatable, especially when the lesions are diagnosed and treated early," Kim said.

Both Kim and Michalski have special training in performing Mohs surgery.

Michalski said sometimes the wounds created by the procedure requires stitches, but often they don't. And because the skin is cut, there is usually a scar - though the surgeon's goal is to minimize it.

What is the follow-up care for basal cell carcinoma?

Michalski said she asks for patients to return after Mohs surgery every six months for two years.