Skin cancer is the most common form of cancer in the U.S., with one in five Americans likely to be diagnosed at some point during his or her lifetime. Here's how diagnosis of skin cancer usually proceeds:
Step 1: Recognition of a suspicious skin lesion
It's common for people to develop spots, freckles, and other skin changes as they age. Most of these changes are benign and no more than a cosmetic nuisance. However, sometimes a spot, nodule, or mole strikes a patient or caregiver as unusual or strange. This may be because of the way it's growing or perhaps because the spot has started to itch or bleed. (For more tips, see 6 Signs You Should See a Doctor About Possible Skin Cancer.)
If you find yourself worried about a skin lesion, make an appointment to see a doctor within a week or so. If the doctor agrees that the spot looks suspicious, you'll want to move on to the next step.
Most doctors examine skin lesions just with the naked eye, but in dermatology offices, they may use a dermatoscope (a type of handheld microscope) to examine a spot on the skin in more detail.
Step 2: Biopsy
If there's any concern of possible skin cancer, the suspicious spot will need to be biopsied. These can be done in a dermatology office as well as in some primary care offices. (Be sure the clinician doesn't just freeze it or shave it.)
Step 3: Histopathology review
A histopathology examination, in which a trained doctor examines the skin cells under the microscope, is essential to diagnosing skin cancer. The doctor will determine whether the skin cells do in fact look like cancer cells and will also try to determine whether the cancer cells have spread into the dermis (the deeper layer of the skin). This microscopic review also allows the doctor to confirm whether the skin cancer is squamous cell carcinoma, basal cell carcinoma, or melanoma.
Step 4: Staging
Staging is the process of checking for the spread of skin cancer to other parts of the body. Melanoma is, by far, the type of skin cancer that's most likely to spread, but squamous cell carcinomas can also metastasize under certain circumstances.
If the skin cancer is melanoma, a doctor will carefully measure how deep into the skin the primary tumor has grown. Depending on the depth of the melanoma and certain other factors, doctors may decide to biopsy nearby lymph nodes to check for spread.
CT scans and other imaging may be ordered if there are signs that the skin cancer may have spread to other parts of the body.
To learn more about how skin cancer staging is done, see FAQ: How Is Skin Cancer Staged?