Hello,
Welcome back to icliniq.com.
Let me address all your concerns, one by one. Can a seborrheic keratosis appear so quickly? (Few months) - Yes, it can appear over few weeks to months. These are also called age spots usually seen in adults and elderly, very harmless. I mentioned seborrheic keratosis because it was appearing raised, and little rough in that picture.
I have other similar looking spots on my face, but they are not rough or raised. Is it normal for a spot like this to be different like that than the others? Lentigines or sun spots, freckles are very common in fair type 2 skin people. If the spot is constantly under friction like rubbing, wearing eyeglasses, with pressure on those spots, it can become slightly thick and appear raised.
If it is a melanoma in early stages, will it still appear that way on a biopsy even if it was previously frozen? A pathologist will be able to see cancerous features even after cryotherapy if the spot is still there. After the biopsy, if there are no cancer cells that means it was not a melanoma or it is totally gone. There are staining methods where they can find even the slightest cancerous change in the tissue. A pathologist will be very cautious while seeing the biopsy if the history of previous melanoma has been provided to him.
Melanoma in situ is the early stage cancer, they have caught it and removed it with wide surgical excision. It is good to be cautious about any similar spots, new moles, changes in the existing mole, like:
A- Asymmetry, B- Border changes/Bleeding, C- Color change (darkening), D- Diameter changes (enlarging).
I can make a clinical diagnosis with what appears on this picture, but any cancerous feature needs to confirmed by biopsy. Allow a week to pass, so that it heals. See if the spot is still there. If yes, then you can go for shave biopsy (minimal pigmentation/scar from shave biopsy).
Hope I have answered your concerns to the best of my knowledge.