What are the odds of two moles at the same time turning into melanoma?

Or what’s the likelihood of two melanomas arising out of nowhere at the same time?    

A mole can transform into melanoma, a cancer with a very grim prognosis when caught at a later stage.

A melanoma can also form out of skin in the absence of a mole.

Melanomas can also grow in areas that have had little to no exposure to sunlight.

Melanoma near the bottom of the foot. Xavier-Júnior, José & Munhoz, Tania & Souza, Vinicius & Campos, Eloísa & Stolf, Hamilton & Marques, Mariângela., CC BY 4.0 creativecommons.org/licenses

“Yes, it is possible for two moles in different locations to both be melanoma simultaneously,” says Alpana Mohta, MD, DNB, a dual board certified dermatologist who specializes in clinical and aesthetic dermatology.

“While relatively uncommon, it is known that melanoma can develop independently in multiple areas of the skin.

“Risk factors, such as a personal or family history of melanoma, genetic predispositions or excessive UV exposure, may increase the likelihood of developing multiple melanomas.”

If you’ve noticed a changing or otherwise suspicious mole anywhere on your body, you still need to be vigilant about examining all of your other moles and never assume that only one mole at a time can ever become a melanoma.

Also keep in mind that in about two-thirds of melanoma cases, the tumor develops in regular skin rather than within a mole.

“It is widely recognized that individuals with melanoma are at an elevated risk of developing other neoplasms, specifically additional melanomas and non-melanoma skin cancers,” says Dr. Mohta.

“A history of melanoma is a significant factor that increases the likelihood of subsequent primary melanomas.

“These multiple lesions can manifest as synchronous or asynchronous lesions, with synchronous lesions defined as subsequent primary melanomas diagnosed within three months of the initial melanoma diagnosis.

“Research studies have reported that multiple primary melanomas range from 0.2% to 8.6% among patients, with approximately 26% to 40% of these cases identified as synchronous lesions.

“The risk of developing another primary melanoma appears highest within the first year following the initial diagnosis — but remains elevated for at least 20 years.”

Lifelong Surveillance

Shutterstock/Africa Studio

A melanoma diagnosis, whether it’s just a single melanoma or two at the same time, requires a lifelong follow-up, meaning, extra-vigilant surveillance of the patient’s skin including annual clinical exams.

Dr. Alpana explains five things you should know about melanoma.

Dr. Alpana Mohta is a dual board certified dermatologist and owner of dralpana.com. Her areas of interest include clinical dermatology, dermatopathology and dermatosurgery. She has over 85 research publications in numerous journals. Apart from her regular medical practice, she is also a medical writer, reviewer and advisor for many companies. 
Lorra Garrick has been covering medical, fitness and cybersecurity topics for many years, having written thousands of articles for print magazines and websites, including as a ghostwriter. She’s also a former ACE-certified personal trainer. 


Top image: Shutterstock/Pixel-Shot