I think i have melanoma. i have a mole that is very big and dark in the center. biopsy or excise?

See dermatologist: You should see a dermatologist immediately. They would tell you what they think it is. They usually would do a biopsy and if proven to be a melanoma- would do a wide resection with negative margins and also many times would do lymph node evaluation/sentinel lymph node biopsy as indicated. See your dermatologist now and go from there.

Excise: Its very difficult to tell if a skin lesion is malignant or benign, or if malignant what type of cancer without seeing it under the microscope, but if the lesion can be completely excised without causing a great deal of trouble(largely contingent upon where it's located)i would favor that approach. If its a different type of primary skin cancer this completes treatment;melanoma needs further rx.