How do you destinguish carcinoma in situ and dysplasia for the pathology questions on the boards. Is there a rule of thumb? Wouldn't you need invasiveness to be considered a carcinoma?

Thanks everyone for your help.

carc. in situ is just when dysplasia involves the entire thickness of epithelium. dysplasia can be a change in just a few cells or a portion of the tissue but when it involves the entire thickness and is not invasive than it is carc in situ.

Just remember your CIN I-CIN III classification. CIN III is to the basement membrane = carcinoma in situ. This holds for all carcinoma in situ (which essentially means localized).

Remember, carcinoma just signifies a malignancy of epithelial cells, while sarcoma describes a malignancy of connective tissue.