How small can an invasive melanoma be and metastasize?

Hi doctor,

I am wondering about how small melanomas can be in diameter to reach metastasis. I have read an article that an invasive micro melanoma can be as small as 0.11 mm in thickness, but I have also read articles saying us to look for moles larger than 6 mm in diameter.

However, I have read another article showing data from a study telling that the diameter of melanomas are more than ten times the thickness. Is this relation correct and if so I guess that the recommendations to look for 6 mm diameter moles relate to catching micro melanomas before they reach metastasis at about 0.4 mm? Kindly give your opinion.

Thank you.

Hi doctor,

Thank you for your reply. This is a surprising answer. I guess when we talk about melanoma it can only relate to skin cancer. Can a tiny melanoma on the skin from the beginning spread to other places? If that is true then there are cases where they are impossible to treat before spreading to other places. And, in some cases even from the start of melanoma cannot get cured. Kindly give me your suggestions.

Kindly help.

Hi doctor,

Thank you for your reply. But can a lymphatic channel be connected with the superficial layer of the skin? I thought it is only located below the superficial layer. It must be extremely rare with cases as tiny as below 1.6 mm diameter.

However, a science article from three decades ago stated only one case. In recent times, a case report reviewed dermatoscopy and dermatopathology findings of a tiny invasive melanoma in a 38-year-old patient who had more than 100 nevi with the smallest diameter ever of a reported melanoma of 1.6 mm. Can you please share your thoughts on this?

Kindly help.