Itโs P+Pโs birthday! Hereโs to one year of interesting diseases! Today I thought it would be fun to learn about the basic types of tumours. There is also a quiz below if you want to test out your histopathology skills!
๐๐ฎ๐ฆ๐จ๐ฎ๐ซ๐ฌ ๐ก๐๐ฏ๐ ๐ญ๐ฒ๐ฉ๐๐ฌ?
Yes! Tumours are basically just an excessive proliferative of a group of cells, due to the cells losing the โbrakesโ on their growth and cell division. Each tissue has a variety of cell types within it, and any of these cells can potentially develop into a tumour. This is why there are so many different kinds of cancer!
There are actually three types of cells that tumours most commonly arise from: ๐๐ฉ๐ข๐ญ๐ก๐๐ฅ๐ข๐๐ฅ ๐๐๐ฅ๐ฅ๐ฌ, ๐ฆ๐๐ฌ๐๐ง๐๐ก๐ฒ๐ฆ๐๐ฅ ๐๐๐ฅ๐ฅ๐ฌ and ๐ซ๐จ๐ฎ๐ง๐ ๐๐๐ฅ๐ฅ๐ฌ. We use the cell of origin and its ๐ฆ๐๐ฅ๐ข๐ ๐ง๐๐ง๐๐ฒ (how nasty it is) to name the tumour, which is pretty handy! This means that if you have the name of the tumour, you can generally figure out what cell type it came from, and how bad it is.
๐๐ฉ๐ข๐ญ๐ก๐๐ฅ๐ข๐๐ฅ ๐๐๐ฅ๐ฅ๐ฌ
Epithelial cells are ๐ฅ๐ข๐ง๐ข๐ง๐ cells, and can be found all over the body! The most common epithelial cell populations are the ๐ฌ๐ค๐ข๐ง, the lining of the ๐ ๐๐ฌ๐ญ๐ซ๐จ๐ข๐ง๐ญ๐๐ฌ๐ญ๐ข๐ง๐๐ฅ ๐ญ๐ซ๐๐๐ญ and the lining of the ๐ซ๐๐ฌ๐ฉ๐ข๐ซ๐๐ญ๐จ๐ซ๐ฒ ๐ญ๐ซ๐๐๐ญ. Their main purpose is to regulate the flow of materials from an open area (like the inside of the gut) into the body. These cells have a characteristic ๐ฉ๐จ๐ฅ๐ฒ๐ ๐จ๐ง๐๐ฅ, or rectangular, shape to them.
To name these tumours, we first decide if they are ๐๐๐ง๐ข๐ ๐ง (not too angry) or ๐ฆ๐๐ฅ๐ข๐ ๐ง๐๐ง๐ญ (angry), then what the epithelial cell population they came from is. If they are benign, we call them an ๐๐๐๐ง๐จ๐ฆ๐. If they are malignant, a ๐๐๐ซ๐๐ข๐ง๐จ๐ฆ๐. So for example, if we had a malignant tumour of the ๐ฌ๐ช๐ฎ๐๐ฆ๐จ๐ฎ๐ฌ ๐๐๐ฅ๐ฅ๐ฌof the skin surface, we would call it a ๐ฌ๐ช๐ฎ๐๐ฆ๐จ๐ฎ๐ฌ ๐๐๐ฅ๐ฅ ๐๐๐ซ๐๐ข๐ง๐จ๐ฆ๐.
๐๐๐ฌ๐๐ง๐๐ก๐ฒ๐ฆ๐๐ฅ ๐๐๐ฅ๐ฅ๐ฌ
Mesenchymal cells are the structural cells that make up the majority of tissues. Even tissues like bone, fat and cartilage are considered to be mesenchymal! These cells are typically ๐ฌ๐ฉ๐ข๐ง๐๐ฅ๐ shaped, meaning elongated with thinned ends.
These tumours are named in a similar fashion, but using suffixes. For example, a benign mesenchymal tumour arising from the fat (๐ฅ๐ข๐ฉ๐ข๐) is called a ๐ฅ๐ข๐ฉ๐จ๐ฆ๐. So the suffix -oma is added to the tissue name. A malignant tumour of the fat would be called a ๐ฅ๐ข๐ฉ๐จ๐ฌ๐๐ซ๐๐จ๐ฆ๐, adding the suffix -sarcoma.
๐๐จ๐ฎ๐ง๐ ๐๐๐ฅ๐ฅ๐ฌ
The round cells are better known as ๐ฐ๐ก๐ข๐ญ๐ ๐๐ฅ๐จ๐จ๐ ๐๐๐ฅ๐ฅ๐ฌ, and have a characteristic ๐ซ๐จ๐ฎ๐ง๐ shape as you might have guessed from the name! These cells make up the majority of our immune system, and can be found patrolling all tissues of the body looking for invaders.
As far as naming goes, tumours of these cells are almost always considered to be malignant. One of the main features of malignancy is ๐ฆ๐๐ญ๐๐ฌ๐ญ๐๐ฌ๐ข๐ฌ, or spreading to other tissues via the bloodstream or lymphatics. In the case of round cellsโฆ theyโre already within the bloodstream! So they are bad news bears right from the start.
Technically, they are part of the mesenchymal cell family, even though we consider them to be a different cell population. So, they have a similar naming scheme to the mesenchymal cells. For example, a tumour of the ๐ฅ๐ฒ๐ฆ๐ฉ๐ก๐จ๐๐ฒ๐ญ๐๐ฌ is called a ๐ฅ๐ฒ๐ฆ๐ฉ๐ก๐จ๐ฌ๐๐ซ๐๐จ๐ฆ๐. Pathologists are often lazy though so you may hear it referred to as a ๐ฅ๐ฒ๐ฆ๐ฉ๐ก๐จ๐ฆ๐, even though this implies that this tumour is benign.
๐๐ก๐จ๐ญ๐จ๐ฌ
1-3) Examples of tumours arising from the different cell populations! If you think you can tell them apart, try the quiz on our website ๐
๐๐จ๐ฎ๐ซ๐๐๐ฌ
Zachary JF. Pathologic Basis of Veterinary Disease, Sixth Edition.
Photos ยฉ Noahโs Arkive contributors Harvey/Raskin, Yin, Knoll, Harmon, Sagartz, Wells, King, Howard, Domingo licensed under CC BY-SA 4.0.
Photos ยฉ Noahโs Arkive contributors Ward, Harmon, Luginbuhl, Ramos, Wells, Hall, Dick, Knoll, King, Hafner/Hill, Eastep, Kazocos, Ramos-Vera, Rech, Bryan licensed under CC BY-SA 4.0.ย
