What is Mohs surgery? The precise technique used to remove skin cancer from Joe Biden

Former president Joe Biden underwent a common surgery to remove skin cancer from his forehead, officials have revealed.

A White House spokesperson told the Daily Mail on Thursday that Biden, 82, recently had Mohs surgery, which is used to remove certain types of skin cancers, including some melanomas, basal cell carcinoma, squamous cell carcinoma, and other less common skin cancers.

It's the same procedure his wife and former First Lady Jill Biden underwent in 2023.

The news was confirmed after Biden sparked health concerns when he stepped out of a church in Delaware earlier this month with what appeared to be a large gash on his head.

In August, Biden was seen with a bandage covering the same spot on his forehead at the funeral for former governor and US Representative Mike Castle.

Biden previously had a basal cell carcinoma removed from his chest in 2023, and Dr Biden had the same cancer removed from her eye in the same year. It's unclear which form of skin cancer he had removed this most recent time.

The former president is also currently undergoing treatment for stage four prostate cancer. That disease has spread to his bones. It's unclear if the skin cancer has spread elsewhere.

Mohs surgery is performed in an outpatient setting and typically takes a few hours. It's usually done with local anesthesia to numb the area, meaning patients are awake.

It's unclear if Biden was awake for the procedure and when exactly it took place.

The objective of a Mohs procedure is to excise as much cancerous skin tissue as possible while also doing as little damage to the surrounding healthy tissue as possible. It's a gradual process and layers of skin are removed in steps.

First, the surgeon uses a scalpel to remove the surface level cancerous skin tissue with the understanding that there might be more cancerous tissue beneath the surface, as the bulk of skin cancer is usually hidden under the surface.

The surgeon maps out where on the body the cancerous tissue was extracted, takes that tissue sample to the lab, dyes it, and cuts it into sections. Specialized technicians place those tissue samples on slides to be investigated under the microscope.

The doctor then examines the edges of each section of tissue for evidence of remaining cancer. If the surgeon finds cancer cells under the microscope, their location is marked on the map.

The process is repeated until the doctor can find no evidence of cancer in the sampled tissue.

Some wounds will be big enough to require sutures to close. They typically heal within a couple of weeks. Smaller wounds can heal by themselves in about a month.

Typically people are able to leave between two and six hours after the outpatient surgery, though the timing depends on the size of the area effected.

The procedure is extremely common. Mohs surgery is performed on over 876,000 tumors per year in the United States.

Certain types of skin cancers treated by this procedure - basal cell and squamous cell carcinomas - are on the rise. Roughly 1.8million cases of squamous cell carcinomas are reported annually.

Over the past 30 years, incidences of squamous cell carcinomas have spiked 200 percent, according to the Skin Cancer Foundation.

Basal cell carcinoma, meanwhile, is the most common form of skin cancer and the most frequently occurring form of all cancers. An estimated 3.6million cases are diagnosed each year in the US alone.

The rising rates of skin cancer are likely due to better detection and diagnosis capabilities as well as increased exposure to ultraviolet light, more time spent on outdoor activities, changes in clothing style, increased longevity, ozone depletion, genetics and in some cases, immune suppression.