Diagnosing Basal & Squamous Cell Skin Cancers

NYU Langone doctors diagnose basal and squamous cell skin cancers with a physical exam and the results of biopsy.

Skin Examination

A dermatologist can sometimes tell by looking at the skin whether you might have a basal or squamous cell carcinoma. He or she may also find precancerous growths called actinic keratoses.

The doctor can also perform dermoscopy, in which he or she examines your skin with a dermatoscope, a device that features a lens that lights and magnifies the skin. This allows him or her to look deeper into the skin to see the distinguishing features of a basal or squamous cell cancer or an actinic keratosis.


Any suspicious growths are biopsied, meaning tissue is removed for examination under a microscope. A dermatopathologist, a doctor who specializes in identifying skin diseases under a microscope, looks for signs of basal and squamous cell cancers or an actinic keratosis. The procedure is performed in the doctor’s office using local anesthesia, which is injected into the skin.

Your doctor may use one of several types of skin biopsies.

Shave Biopsy

A shave biopsy involves removing a growth that forms a bump on the skin. Your doctor uses a small surgical blade to shave off a thin piece for examination and then applies a bandage.

Punch Biopsy

For small growths that lie flat against the skin, physicians may use a tool called a punch, which resembles a tiny cookie cutter. The skin may be closed with a stitch or stitches, as needed.

Excisional Biopsy

For larger growths, a doctor may perform an excisional biopsy. This procedure involves removing the entire growth with a small scalpel, or cutting tool, and is performed with local anesthesia in the doctor’s office. The doctor usually closes the skin with stitches.

Lymph Node Biopsy

Nonmelanoma skin cancer is unlikely to spread, but when it does it may travel to the lymph nodes, immune system glands that trap invaders such as viruses and bacteria. A doctor may perform a lymph node biopsy if he or she notices a swollen node near a possible basal or squamous cell carcinoma.

A doctor may also order a lymph node biopsy if surgery shows that skin cancer has spread to nerves or blood vessels in the area. Squamous cell cancer is more likely to spread than the basal cell variety.

To perform a biopsy, your doctor uses a local anesthetic to numb the skin and inserts a small needle into a lymph node to withdraw tissue and fluid. The sample is then examined under a microscope. The doctor may also remove one or more lymph nodes, which gives pathologists more tissue to examine in determining whether the cancer has spread.