Should I have an excisional biopsy because doctor thinks it could be melanoma?

Probably. If the lesion is a non-melanomatous skin cancer, complete excision will be curative, while if its melanoma he'll need to do a wider excision and possibly a lymph node dissection, depending on the site. So unless there is some cosmetic contraindication i see nothing to lose with the excisional biopsy.
Depends. Typically dermatologists do a shave biopsy. They are appropriate when well-trained people do it (usually derm - most general surgeons and gp's do not have that specific training.) the problem with excisional biopy is that it may complicate the required surgery if it is a melanoma. Like most things - go to a qualified specialist.

Related Questions

If a dr thought a mole was melanoma, do they usually do an excision biopsy as opposed to a shave?

Excisional biopsy. An excisional biopsy is often used when a wider or deeper portion of the skin is needed. Using a scalpel, or punch biopsy tool, a full thickness of skin is removed for further examination, and the wound is sutured. Superficial shave biopsies are generally discouraged for the removal of suspicious pigmented lesions since they may not allow for optimal pathologic interpretation of the skin sample. Read more...
Either is fine. The first step in melanoma diagnosis is to obtain a biopsy of the lesion. Whether this is performed as a punch biopsy or a shave biopsy doesn't seem to matter. The key is getting the tissue to the pathologist to make a diagnosis. Read more...

Level 3 cervical lymphnode had abnormal morphology on ct, getting an excision biopsy soon. What do abnormal morphology mean? Doc suspects lymphoma

Shape/Size Mostly. CT shows nodal shape, size and if it is has fat (a good thing). Most nodes are oval or kidney shaped. If they are round and big, they may be involved in something like lymphoma. Sometimes infection can do this too, so it is not a slam dunk. I'm afraid you'll just have to wait it out for the path report as CT is non specific. MR with fancy contrast is better but still not as good as Bx. Read more...