Mixed tumour of the vagina.

A 33-year-old Japanese woman presented with a polypoid 2.5 x 2.5 x 1.9 cm mass located in the posterior wall of the lower vagina. Microscopically, the tumour was composed of benign epithelial and stromal-type elements. Predominant epithelial elements were mucinous glands with squamous metaplasia and islands of mature squamous epithelium. The stromal-type cells showed reticular or short fascicular patterns with a transition to the epithelial elements. There was no dual epithelial-myoepithelial combination in the glands as seen in so-called mixed tumours (pleomorphic adenomas) of the salivary gland. Immunohistochemically, the epithelial elements were strongly positive for cytokeratin, PKK1 and epithelial membrane antigen, while the stromal-type cells co-expressed PKK1 and vimentin. Staining for S-100 protein, muscle actin, alpha-smooth muscle actin, desmin, and CD34 was uniformly negative in the tumour cells. The DNA pattern was diploid. The patient is alive and well without recurrence for 50 months after excision. These results indicate that an epithelial cell proliferation, probably of the remnant vestibular gland, plays a major role in the development of mixed tumours of the vagina.