Only doctors can accurately diagnose a spot as skin cancer through the use of a biopsy, notes Mayo Clinic. During a biopsy, doctors cut out some or all of the affected skin, and a pathologist analyzes it to determine if the skin cells are cancerous.
Doctors choose different types of biopsies to determine if a spot is skin cancer depending on whether it is possible to remove the entire skin growth, states Mayo Clinic. Doctors conduct punch biopsies by pressing a circular blade into the skin to remove a lesion. During an excisional biopsy, doctors remove the entire growth along with some normal-appearing skin. If doctors cannot remove the entire affected area, they conduct an incisional biopsy by removing only the most irregular part of the skin.