The adenoma-carcinoma sequence applies to epithelial tumours of the papilla of Vater.

Adenomas of the papilla of Vater are relatively rare tumours. They are of particular interest, not only because of their particular topography, but also because the adenoma-carcinoma sequence - accepted in the colorectum - has also been postulated to apply to the papilla of Vater. In fact, ampullary adenoma is often considered to be a precancerous lesion. To investigate this hypothesis, we reviewed the surgical specimens obtained during Whipple's procedures carried out to treat histologically confirmed carcinoma of the ampulla. A total of 37 surgical specimens obtained since January 1991 were reexamined for the presence of coexisting adenomatous structures. Such adenomatous residues were confirmed in 24/37 (65 %) cases. In 13/37 (35 %) cases, no residual adenoma was found. A comparison of the two groups revealed that detection of coexisting adenomatous structures decreased with increasing tumour progression. In similar manner, this also applied to the degree of malignancy: with increasing grade of malignancy the rate of detectable adenomatous structures decreased significantly. It may be assumed that these observations are due to the 'overgrowth' of preexisting adenomas by carcinomatous tissue. Further evidence is provided by the histological observation of transitional stages from adenoma with mild, moderate and severe cellular atypia to invasive carcinoma. These findings support the hypothesis of an adenoma-carcinoma sequence.