Oral leukoplakia

Oral leukoplakia is a white patch on the mucosa of the mouth, the moist, soft layer that lines it on the inside. The name comes with a catch: a white patch is only called leukoplakia when it can't be explained as any other known lesion. It is closely tied to tobacco and is considered a potentially malignant disorder, meaning a lesion that has the potential to turn into cancer.

Here's what happens inside. The epithelium is the layer of cells that forms the surface of your mouth. When it's exposed to a carcinogen, a substance that can cause cancer, its first response is to grow faster. That's called hyperplasia: more cells get made, and they get made more quickly. Think of a copier running at top speed: the faster it spits out pages, the more likely it is that one comes out with mistakes. Something similar happens with cells. That rushed pace of division makes it easier for their genetic material to get damaged even further, and that damage keeps pushing them toward malignant transformation, the path to cancer.

Not every leukoplakia looks the same. There are two main types. Homogeneous leukoplakia forms even white patches, the same shade across the whole surface. Non-homogeneous leukoplakia is irregular and mixes red patches with white ones, and it's the type more likely to become malignant.