Also known as CIN3 (Cervical Intraepithelial Neoplasia grade 3) this is a histological term that can only be applied after a biopsy has been performed with the aid of a colposcope.
After contact with a potentially oncogenic Papillomavirus, infected cells can progressively lose control of their own rate of cell division and divide more rapidly than normal.
The cell abnormalities from the biopsy sample spread throughout the mucous membrane much like a fire starting through all the floors of a building.
A further analogy can be used to explain dysplasia vis a vis cancer. Cancer is like a dark sky full of clouds that rain so much the rain water penetrates through to the water table. This symbolises how cancerous cells travel, or spread to different locations or parts of the body, called metastases.
Following on from our analogy, severe dysplasia is like a dark sky heavy with clouds that have not yet rained, and whilst it is possible that the clouds will rain, as long as the rain is light there is only a slight risk of the water spreading. This is therefore time to take the clouded area away before any storm arises.
This type of lesion can also revert spontaneously, though this is far from being frequently the case. Indeed, the possibility of the lesions progressing to invasive cervical cancer is higher and so it is important to promptly, but calmly, consider an appropriate treatment plan.
The delay between diagnosis and development of a cancer can take up to several years, however it is appropriate to treat these lesions.