Code 0: In Situ
- Translates as “in place”
- Can only be made microscopically (histologically confirmed)
- Presence of malignant cells within cell group from which they arose
- Fulfills pathological criteria for malignancy
- No invasion of basement membrane
- No invasion of supporting structures of the organ on which it arose
Pathologists have many ways of describing in situ cancer
- No penetration of/or below the basement membrane
- No stromal invasion
Organs and tissues that have no epithelial layer cannot be staged as in situ, since they do not have a basement membrane (e.g., sarcomas). The SS2018 manual lists the Chapters that cannot have in situ (see page 10).
Source: Adapted from an illustration by Brian Shellito of Scientific American, as printed in Cancer in Michigan, The Detroit News, Nov. 1-2, 1998.
Updated: September 18, 2018