What is Malignant Melanoma?
Melanoma is a cancer that starts in the cells of the skin that produce color. Malignant means that this cancer is capable of spreading to other parts of the body as it grows.

Melanoma in the Foot
Melanoma in the foot is typically unnoticed by most patients, which unfortunately allows it to progress to a stage where treatment is more difficult, and thus has a higher mortality rate. This means patients should pay special attention to their feet for signs of melanoma, as well as other parts of their body.

Causes of Melanoma
Usually, melanoma is caused by too much exposure to the sun or tanning beds, both of which give off ultraviolet (UV) radiation. While anyone can get melanoma, some factors can make a person more prone, including fair skin, skin that freckles, having blonde or red hair, blistering sunburns before the age of 18, or numerous moles, especially when one is young. 

What Should You Look For?
Melanoma can appear anywhere on the body, even areas that aren't regularly exposed to sunlight. It usually appears as a spot on the skin that is mostly brown, black, or blue, though sometimes it can appear mostly red or even white. However, it should be noted that not all skin discolorations are melanomas. Here are four signs you should look for when inspecting moles or other spots on your body:

• Asymmetry: melanoma is usually asymmetric; one half is shaped differently from the other
• Border: The edge of a melanoma is usually irregular; ragged, notched, or blurred.
• Color: Melanoma is typically a mix of colors, rather than a single hue
• Diameter: Melanoma will grow in size, where a mole would remain small. Any spot larger than 5mm (the size of a pencil eraser) should be cause for concern. 

If you notice any of these signs on your foot, it's important that you see your podiatrist as soon as possible for evaluation. Likewise, if they appear on another part of your body, you should seek your primary care provider for examination. It should be noted that if you notice discoloration underneath your toenails of  any size  (besides that which has been caused by dropping something on the toe, or stubbing it) you should seek your podiatrist right away. 

Diagnosis
Your podiatrist will ask you some questions regarding the changes in size or color to the spot in question, if it's old or new, or how quickly you've noticed change, if any. They will also look at the spot to determine if a biopsy is necessary.