Intratesticular mucinous cystadenoma: immunohistochemical comparison with ovarian and colonic tissue.

We report a case of a primary intratesticular mucinous cystadenoma in an asymptomatic 39-year-old man. The mass was found incidentally during a consultation for infertility. Pathologic examination of the orchiectomy specimen revealed a unilocular cyst lined with bland mucinous epithelium and mucinous extravasation, consistent with a diagnosis of mucinous cystadenoma. Foci of bone were also found in association with extensive chronic inflammation. Immunohistochemical stains performed showed immunoreactivity for cytokeratin 7, and nonreactivity for cytokeratin 20, CA125, chromogranin, and synaptophysin. The immunohistochemical staining patterns of the present case are compared with those of known mucinous cystadenomas of the ovary and nonneoplastic colonic mucosa. The histogenesis of this entity is discussed in light of the literature and the immunohistochemical findings in this rare case.