A skin examination by a dermatologist is the way to get a definitive diagnosis of skin cancer. In many cases, the appearance alone is sufficient to make the diagnosis. A skin biopsy is usually used to confirm a suspicion of skin cancer.
http://www.medicinenet.com/skin_biopsy/article.htm
A negative margin or clear margin indicates there are no tumor cells at the margin. That means the cancer is contained in the area nearest to the tumor. A close margin means that the space between the cancerous tissue and surrounding normal tissue is less than about 3 millimeters (0.118 inch). If you have a biopsy resulting in a cancer diagnosis, the pathology report will help you and your doctor talk about the next steps.
http://www.nationalbreastcancer.org/breast-cancer-biopsy
The removed cells are examined under a microscope and further tested to check for the presence of breast cancer. A biopsy is the only diagnostic procedure that can definitely determine if the suspicious area is cancerous. The good news is that 80% of women who have a breast biopsy do not have breast cancer.
http://www.nationalbreastcancer.org/breast-cancer-biopsy
The sample taken during a biopsy is often very small, sometimes the size of a grain of rice. The sample size is just large enough for laboratory technicians to test for various issues that could be the cause of a skin lesion. However, the biopsy sample may be larger if the entire lesion is removed. There are several ways your doctor can collect a skin sample. The procedure your doctor chooses will depend on your individual circumstances. A doctor who specializes in skin (dermatologist) is typically the doctor who performs a skin biopsy.
http://www.healthline.com/health/skin-lesion-biopsy
1 Once the right sample is taken, your doctor will remove the skin sample with tweezers and close the incision with a single stitch.  Excisional biopsy: This is used to remove the entire lesion. Your doctor makes an incision and, going as deeply as necessary, removes the entire lesion.
http://www.healthline.com/health/skin-lesion-biopsy
Excisions are usually larger and deeper and are used to completely remove an abnormal area of skin such as a skin cancer. These are not technically biopsies since the goal of this procedure is to remove the whole lesion rather than to remove a small portion to make a diagnosis.
http://www.medicinenet.com/skin_biopsy/article.htm
After a Skin Lesion Biopsy. After the tissue sample is taken, it’s sent to a laboratory for testing. It usually takes about one week for the results to come back, but some tests can take longer. If it’s an emergency situation, like an aggressive infection or cancer, your doctor may put a rush on the results.
http://www.healthline.com/health/skin-lesion-biopsy
After the biopsy, the skin sample is fixed in special solution, and thin sections of the tissue are cut and placed on microscope slides. The slides are stained for examination by a doctor (usually a dermatologist or pathologist).
http://www.medicinenet.com/skin_biopsy/article.htm
Once the biopsy is complete, a specially trained doctor called a pathologist examines the tissue or fluid samples under a microscope, looking for abnormal or cancerous cells. The pathology report, which can take one or two weeks to complete, is sent to the patient’s doctor.
http://www.nationalbreastcancer.org/breast-cancer-biopsy
Core needle biopsy is the procedure to remove a small amount of suspicious tissue from the breast with a larger “core” (meaning “hollow”) needle. It is usually performed while the patient is under local anesthesia, meaning the breast is numbed.
http://www.nationalbreastcancer.org/breast-cancer-biopsy
what is it called when you send a skin sample to a lab to see if its cancerous
When you send a skin sample to a lab to see if its cancerous, it is called a skin biopsy. When you send a skin sample to a lab to see if its cancerous, it is called as skin biopsy.  when you send a skin sample to a lab to see if its cancerous is called as skin biopsy.