A doctor has shared a shocking video showcasing the 'worst' skin cancer he's ever diagnosed.

Skin cancer is one of the most common cancers in the United States, with the American Academy of Dermatology Association estimating that one in five Americans will develop the condition in their lifetime.

Melanoma, the deadliest form of skin cancer, accounts for about 1% of all cases in the US, while the majority of cases are basal and squamous cell carcinomas.

According to the NHS, the primary symptoms of skin cancer include changes to the skin, existing moles, or the appearance of new moles.

Dr. John O'Bryen, known as 'skincaredoctor' on TikTok, has been raising awareness about skin cancer and teaching people how to recognize the signs, even when they aren't immediately obvious. As a specialist at Body Scan Skin Cancer Clinic in Australia, he has emphasized that not all melanomas appear as freckles or moles. In a recent video, he revealed the 'worst' type of skin cancer he has ever diagnosed.

Dr. O'Bryen explained in his video: "A man came to me last week, concerned about a new lump on his arm. It was red and had been growing quickly."

He then showed a close-up video of the lesion using a 'dermatoscope', revealing the spot was pink and white in color.

The doctor noted that it measured 4mm on the Breslow thickness scale, which is used to assess the depth of melanoma from its outer layer to the deepest point of the tumor.

On the surface, it appeared to be a slightly raised red lump, but under the microscope, it showed 'white polarising lines' and 'polymorphous vessels.' The doctor quickly diagnosed the patient with nodular melanoma, a particularly dangerous type that grows rapidly and is associated with the highest fatality rates.

According to the Cleveland Clinic, nodular melanomas appear as 'firm, raised, discolored growths' on the skin, sometimes resembling a blood blister. These spots may itch, sting, or bleed.

Nodular melanomas can have a dome-shaped appearance with either a smooth or a 'crusty' texture, often described as similar to cauliflower. These tumors grow both above and below the skin, but most of the cancer is beneath the surface, much like an iceberg.

Nodular melanoma is the second most common type of melanoma, accounting for 15 to 20 percent of diagnoses. This type of skin cancer is responsible for about 50% of all melanoma-related deaths.

In the caption of his viral video, Dr. O'Bryen wrote: "Scary! Not all melanomas are brown and black!"

He went on to explain that he performed an excisional biopsy of the lesion and that the patient would be referred to a melanoma surgeon and medical oncologist.

Dr. O'Bryen also mentioned that his magnifying tool, the Heine Delta 30 Pro dermascope, "continues to assist me in diagnosing skin cancers" and that it helped him diagnose and treat over 1,000 people in the previous year.