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The tumors show
papillary proliferations of columnar mucus-secreting epithelial cells replacing the normal duct epithelium.
Benign intraductal papillary mucinous adenomas
show a simple papillary or
villous growth pattern and there is no cellular atypia.
Borderline
variants show an irregular papillary growth with moderate epithelial dysplasia and
frequent mitoses.
In intraduct papillary mucinous carcinoma
the papillary proliferations show marked irregularity, cribriform
gland formation, and marked nuclear abnormalities. |