Benign vs. Malignant: Definition, Characteristics & Differences
This lesson will talk about the common distinctions between malignant and benign tumors. We’ll discuss how they may look or feel and how it is that they may look differently under the microscope as well.
The Bad and the Good
What makes someone good or bad? Perhaps you can come up with some characteristics. Good people are usually kind, gentle, willing to help others, and tend to smile a lot. Bad people are those that harm defenseless individuals, cannot control their anger, or are sitting in jail. The way we can group good vs. bad characteristics in people can also be applied to the world of trying to figure out whether a tumor is really bad or not.
Benign vs. Malignant Tumors
There are two main classifications of tumors. One is known as benign and the other as malignant. A benign tumor is a tumor that does not invade its surrounding tissue or spread around the body. A malignant tumor is a tumor that may invade its surrounding tissue or spread around the body.
I sometimes compare benign tumors to gentle European bees that typically don’t bother people or cause them much harm. If you get too close, though, you might get stung, but that’s usually it. Similarly, benign tumors on rare occasion may actually be life-threatening, but as a general rule aren’t nearly as bad as the malignant tumors.
The malignant tumors are like those killer bees. You don’t even have to be doing anything to them or be anywhere close to their hive, and they’ll just spread out and attack you en masse – even kill you if they’re severe enough.
Macroscopic Differences
Just like you’d want to tell the differences between gentle bees and killer bees, you’d want to know the very general and stereotypical characteristics between benign and malignant tumors. For instance, we know that killer bees are usually bigger than gentler bees. Well, we can use these types of visually observable or palpable differences for tumors as well.
Benign tumors usually grow very slowly, while malignant tumors grow more quickly in size. To put that into a more specific perspective, it may take months or years for a benign tumor to change significantly in size, while malignant tumors can grow appreciably in just a few weeks. Benign tumors are also more likely to be freely movable within or on the tissue they reside on, while malignant tumors may be more difficult to move around due to local tissue invasion.
Further still, benign tumors tend to be very well-circumscribed when looked at grossly, that is to say macroscopically, with imaging modalities such as MRI, or under the microscope. This means the edges of the tumor are usually very distinct and demarcated in a certain shape. This is in contrast to malignant tumors that may have an irregular shape; it may be difficult to tell where the tumor starts and ends. What’s more, malignant tumors are more prone to color changes and ulceration than benign tumors.