Stage 0 melanoma in a mole vs not in mole

The short version: whether a stage 0 melanoma sits inside an existing mole or starts on normal skin changes how closely it gets watched, but not the core treatment, which is complete removal.

No studies came back for this question, so I can't ground the specifics in records. What I can tell you is general clinical knowledge, flagged as such, not from evidence in front of me.

Stage 0 means the abnormal cells are confined to the top layer of skin, the epidermis. They have not invaded deeper. That is why the treatment is surgery to remove the spot with a small margin of normal skin, and why the cure rate is very high. The distinction you are asking about is real but secondary. A melanoma growing out of a long-standing mole (the "arising in a nevus" type) is often caught earlier because the mole was already being watched, and it tends to be a slower-growing subtype. A melanoma starting on normal skin is more often the type that appears without warning. Neither changes the fact that stage 0 is treated by excision.

What does change is follow-up. A melanoma in a pre-existing mole can be harder to spot on skin checks because it blends into the mole's own pattern, so the surveillance schedule and the dermatologist's eye matter more. The staging itself, and the decision to remove, does not hinge on where it started.

The honest limit: I cannot give you recurrence rates or survival figures for the two types from memory, and I won't invent them. The study that would settle it is a cohort comparing outcomes of nevus-associated versus de novo stage 0 melanoma after excision, with long follow-up.

My call: the mole-versus-normal-skin distinction affects monitoring, not the surgery, and stage 0 is highly curable either way. Confidence: moderate on the treatment, low on any outcome difference between the two types.