Micropapillary carcinoma of the parotid gland arising in mucinous cystadenoma

We describe a 45-year-old man who had a 2-year history of a slowly enlargin g tumor in the left parotid gland. Histologically, the tumor was a mucinous cystadenoma with focal apocrine differentiation, which revealed a widespre ad invasive micropapillary adenocarcinoma component. A rim of lymphoid tiss ue surrounded the margins of the micropapillary carcinoma. The invasive mic ropapillary adenocarcinoma component was morphologically identical with the invasive micropapillary carcinoma of the mammary gland. The tumor is diffe rent from so-far recognized salivary gland tumor entities.