Diagnosing invasive cancer
It is particularly important for the colposcopist to correctly diagnose invasive cancers, especially early invasive cancers. Invasive lesions will have some or all of the following features.
- A large, dense acetowhite area with elevated margins in the transformation zone is suspicious of invasive cancer. The lesion may have an undulating surface, especially near the external os. The lesion often appears to impinge on the external os to block it.
- The lesion may extend to the vagina for a variable distance.
- Extensive vascular abnormalities are visible: atypical vessels, coarse mosaic, coarse punctation, or combinations of these.
- Surface irregularity or a molehill-like undulating surface is a characteristic of invasive lesions.
- A dense acetowhite area with erosion of the surface that bleeds easily is suspicious of invasive cancer, especially if it is associated with atypical blood vessels.
- A thick leukoplakia patch in the transformation zone may hide an invasive cancer. A deep punch biopsy or a loop biopsy is required to establish the diagnosis.
- Invasive cancer turns into an iodine-negative area with a bright canary yellow colour after application of Lugol’s iodine.
If the lesion is suspicious of invasive cancer, the distal extent of the lesion should be carefully evaluated. If the vagina is involved, both the staging and the management may be altered.
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