The Dysplasias (Cervical Intraepithelial Neoplasia)
“Plasia” means growth. Dysplasia refers to the disorganized growth of cervical epithelial cells. But before we discuss disorganized growth we should look at what “organized” or “normal” growth looks like. If we look at the left hand portion of the accompanying picture, we can see that the bottom layers of cells are plump and contain nuclei. The top layer of cells is flat (like an omelet) and contains either small or no nuclei. Additionally, the cells are small and do not take up much stain.
The middle portion of the drawing reveals the appearance of dysplastic cells.
Notice that the cells at the bottom are darker (they take up more stain) and the nuclei are very large compared to the cytoplasm of the cell. This is disordered (or dysplastic) growth and can be categorized as “mild” “moderate” or “severe”. When the disordered growth occupies the lower third of cervical “skin” or epithelium we consider it “mild”. It is considered moderate when dysplasia occupies the lower half of the epithelium and when dysplasia occurs in the full thickness of the cervical epithelium we call it carcinoma in situ (CIS).
Many women in the U.S. have carcinoma in situ (or severe dysplasia). However this is almost 100% curable and is not the same as invasive cervical cancer, which is very dangerous and fortunately very rare.
In carcinoma in situ (CIS) the full thickness of the epithelium has abnormal cells but they do not invade into the underlying tissue.
Invasion into the surrounding tissue is what defines a true cervical cancer.
To try and get an understanding of this try rubbing the skin on the back of your hand and notice that it is free of the underlying muscle and tendons—it moves freely with only gentle rubbing.
If the entire thickness of that skin were affected with abnormal cells it would be called CIS. If the entire thickness of that skin were rubbed and found to be attached to underlying muscle and tendons that would be an example of invasive cervix cancer.