Carcinoma in situ, CIS, Severe Dysplasia, and CIN 3 (Cervical Intraepithelial Neoplasia Grade III) are essentially synonymous terms.

This is not cancer, although it sounds like it is. This is considered a pre-cancerous problem. Carcinoma in situ means:

• There are abnormal cells extending the full thickness of the skin.
• These cells individually look just like cancer cells.
• If the cells were invading through the basement membrane into the underlying tissues, this would be considered cancer.
• Because they have not invaded through the basement membrane, this is, by definition, not cancer.

Carcinoma in situ is considered by many authorities to be clinically equivalent to severe dysplasia, or CIN 3. It should be promptly and carefully evaluated.

Treatment might consist of eliminating the abnormal cells by freezing them (cryosurgery), vaporizing them (laser), or shaving them off with an electrified wire loop (LEEP). In some circumstances, more extensive surgery in the form of a cervical cone biopsy is required to eliminate the problem.

Hysterectomy is generally not necessary, but under unusual circumstances might be the best treatment.