Sherri writes: I have recently been diagnosed with carcinoma in situ on my cervix. In searching the Web, I'm finding conflicting info about the difference between this, and cancer, and dysplasia. Some places say CIS is the same thing as severe dysplasia, while others list it separately. Can you clarify?

Yes, I've seen it described different ways myself, which led me to check it out pretty thoroughly. I've come to the conclusion that basically, it's the same thing, or there is very little difference between the two.

Severe dysplasia (CIN 3) has, as part of its definition, that it takes up all or almost all of the squamous epithelium in a spot of the cervix. Carcinoma in situ, by definition, takes up the whole squamous epithelium in a spot of the cervix. This means that they are in essence "sitting" on what is called the basement membrane under the epithelium. In both cases, the cells are severely dysplastic (abnormal). The only real difference is that CIN 3 might not quite take up the whole epithelium.

Once the basement membrane is infiltrated, by definition you have cervical cancer, but not until that point. Luckily squamous cell dysplasia and cancers are almost always very slow growing.

Best wishes to you -

Laura

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