Oral monomorphic adenomas.

Monomorphic adenomas of the oral cavity have a predilection for the anterior mouth, particularly the upper lip. Two of the monomorphic adenomas, the inverted ductal papilloma and the canalicular adenoma, are biologically benign, but unfamiliarity with their histopathologic appearance can lead to a misdiagnosis of malignancy. The clinical and pathologic features of each are presented.