The difference between a mole and skin cancer generally comes down to size, shape, color, and elevation. Though skin cancer can often only be truly diagnosed through laboratory tests on suspect moles, it's important to report any suspect moles to a healthcare professional so that you can get treatment as soon as possible if it is cancerous. There are also many things you can do to lower your risk of developing skin cancer, including using sunscreen and avoiding tanning.
Appearance of Moles
Moles tend to be symmetrical, and are usually either circular or oval in shape. Their edges are usually rounded and well-defined, and not irregular. Most are all one color, and they tend to stay that color throughout a person's life. Though some are large, most non-cancerous moles tend to be about the size of a pencil eraser, about 0.25 in (6.35 mm) in diameter. Though moles do sometimes naturally increase in size, particularly those on children, they usually grow slowly, and don't suddenly start to change size or shape.
Appearance of Cancers
Skin cancers in general often have ABCDE characteristics: they tend to be Asymmetrical, have irregular Borders, change Color, have a large Diameter, and are Elevated above the skin. Besides this, each of the three main types of skin cancer — melanoma, basal cell carcinoma, and squamous cell carcinoma — has a specific look. Growths caused by melanoma are typically fast growing or large, have many different colors, and may get red or bleed. Basal cell skin cancer often appears as a pearl-colored bump or red patch, or a patch of thickened or scar-like skin. Squamous cell cancer begins as a small bump that grows slowly, the center of which usually develops an ulcer or sore that does not heal.
When to Seek Medical Attention
The most important rule in assessing the difference between a mole and skin cancer is to check with a medical professional whenever you have doubts. If you have large moles, you may want to take pictures of these, or measurements, to be certain they do not change in size or appearance over time. Seek medical attention right away if you note significant changes in a mole.
Preventing Skin Cancer
You can often significantly lower your risk of skin cancer by avoiding exposure to Ultra Violet (UV) rays. It's best to avoid sun exposure during the middle of the day, and to wear sunscreen when outside, as skin damage resulting from repeated sun exposure is the biggest causal factor in any of the skin cancers. Since tanning beds and sun lamps use UV rays, they can also significantly increase your chances of skin cancer.