Q: What does a dermatologist look for in determining if a lesion is cancerous? How is it confirmed?
A: In evaluating patients for skin cancer, dermatologists look carefully over all areas of the skin, especially those areas that are sun exposed. Skin cancers can arise suddenly over a period of weeks, or they can grow very slowly over a period of years. Often skin cancers will have a different texture from the surrounding skin, feeling very soft or very rough. Some skin cancers can show skin breakdown at the surface, causing easy bleeding if rubbed with a towel or lightly scratched with a fingernail. Basal cell carcinoma, one common type of skin cancer caused by sun exposure, often is skin-colored or pink and can have fine blood vessels evident over the surface. Squamous cell carcinoma also may be skin-colored or pink and often has a scaly, rough surface. Melanomas are most commonly pigmented (dark in color) but can show color variation within the lesion, or even be pink in color.
To confirm whether a lesion on the skin is cancerous or not, a dermatologist will often perform a skin biopsy. There are several techniques for biopsying skin lesions. The most common are termed shave biopsies and punch biopsies. With both methods, the skin is anesthetized with an injection of lidocaine (often mixed with epinephrine to reduce bleeding risk), which can briefly produce a burning sensation in the skin (lasts seconds). Using the shave technique, a blade is used to sample a superficial piece of skin, which is sent to a pathology lab for processing and microscopic evaluation. The patient is resultantly left with a superficial wound similar to an abrasion (think of “skinning your knee”). Using the punch biopsy technique, the skin is similarly
anesthetized and then a special tool is used to remove a circular piece of skin that extends to a greater depth than a shave biopsy specimen (think of a small cookie-cutter for the skin). Because the resulting wound is generally deeper than that produced with the shave technique, punch biopsy wounds often are sutured or packed with an absorbable material to help facilitate healing. The skin specimen is sent to the pathology lab for processing. The time it takes to receive the final pathology report can vary depending on the laboratory used, but it often can take days to up to 1 week.