Mucinous Cystadenoma in the Upper Lip: Report of Two Cases.

Mucinous cystadenoma of the salivary gland is a very rare disease, and only a few cases have been reported. We report here 2 cases of mucinous cystadenoma in the upper lip. The first case was a 57-year-old man and the second was a 42-year-old woman. The tumors were painless nodules with a smooth-surfaced mucosa, and surgical excisions were performed. Histologically, the tumors were surrounded by a fibrous capsule and were composed of multiple cysts lined with columnar epithelial cells. The tumor cells contain mucous substances that reacted with periodic acid-Schiff base and Alcian blue. Immunohistochemical staining revealed that the tumor cells expressed cytokeratin (AE1/3 and CK7), but their immunoreactivity with MIB-1 (Ki-67) was less than 3%. They had negative immunoreactivity for neuroectoderm markers, S-100 protein, and myoepithelial markers, p63, α-smooth muscle actin, and calponin, except for the accompanying myoepithelial-like cells. No recurrences were noted after surgery at 7 years and 1 year, respectively.