Singer Jimmy Buffett died after being diagnosed with Merkel cell carcinoma, a rare type of skin cancer

• Jimmy Buffett, best-known for his song "Margaritaville," died last week.
• He was treated for Merkel cell carcinoma, a rare form of skin cancer, for four years before he died.

Singer Jimmy Buffett died last week, aged 76. According to a statement released on his website on Sunday, he had Merkel cell carcinoma, a rare form of skin cancer.

The billionaire singer is best known for his song "Margaritaville," and for owning the restaurant chain with the same name.

He was diagnosed with Merkel cell carcinoma four years before his death, but had continued to perform throughout treatment, playing to fans at his last show in Rhode Island in early July, according to the statement.

He was taken to a hospice last Monday, and died on Friday surrounded by family, friends, and his dogs.

A friend of Buffett's told TMZ that "He lived his life in the sun, literally and figuratively."

The source said his carcinoma "turned into lymphoma, and we're told that was the cause of death."

The main symptom of Merkel cell carcinoma is a painless nodule on the skin

Merkel cell carcinoma is a disease where Merkel cells in the top layer of skin start to grow out of control.

According to the Mayo Clinic, the main symptom of Merkel cell carcinoma is a fast-growing, painless nodule on the skin, which can be flesh-coloured, red, purple, or blue. It most often develops on areas of the skin that are frequently exposed to the sun, including the head, neck, arms, and legs, according to The National Cancer Institute.

It is a rare form of cancer, with only 3,000 new cases diagnosed in the US per year, according to The Skin Cancer Foundation, and it's 40 times rarer than melanoma.

Sun exposure and pale skin are risk factors for Merkel cell carcinoma

Risk factors for the disease include:

• Exposure to natural or artificial sunlight

• Having a weakened immune system due to disease or taking immunosuppressant drugs

• Having had other types of cancer

• Being over 50 years old

• Being white or having lighter-colored skin

The disease is treatable and has a 65% survival rate

When someone is diagnosed with a Merkel cell carcinoma, the first step is to check whether the cancer has spread to other parts of the body, which can involve a CT scan, a PET scan, or a biopsy.

Surgery, radiation therapy, chemotherapy, and immunotherapy are all used to treat Merkel cell carcinomas, depending on how advanced the cancer is, where it is, and the patient's general health, according to the National Cancer Institute.

The American Cancer Society estimates that people diagnosed with the cancer have a 65% chance of still being alive five years after diagnosis.