Ductal adenocarcinoma can be grossly and microscopically difficult to distinguish from chronic pancreatitis, particularly on frozen preparations.
A diagnosis of adenocarcinoma is favored by the presence of irregular, often incomplete glandular structures lined by atypical cells in the setting of lobular disarray.
Perineural invasion,necrosis, prominent mitotic activity, and mucin production also are helpful features .
It is important to keep in mind that ductal carcinoma and chronic pancreatitis of the adjacent nonneoplastic parenchyma often coexist.