Cytologic features of villous adenoma of the ampullary region.

Villous adenoma of the ampulla of Vater is a rare but distinct pathologic entity. We studied seven brush cytology specimens from four patients with this unusual lesion all of whom had surgical pathologic confirmation and clinical follow-up. The distinguishing cytologic appearance includes the presence of slender, elongate columnar cells arranged singly or in small sheets and clusters. Long, thin, basally oriented nuclei occupy about one third of the cell and have fine, granular chromatin with one or more nucleoli. Although brushings of villous adenoma of the ampullary region may reveal a relatively benign but distinctive morphologic pattern, the aggressive nature of these lesions has been well documented, including those in our patients.