Serous papillary cystic tumor of borderline malignancy with focal carcinoma arising in testis: case report with immunohistochemical and ultrastructural observations.

A 59-year-old white man presented with painless scrotal swelling, a symptom he stated he had had for "several decades." Pathologic examination (conventional stainings, immunohistochemistry, and electron microscopy) revealed a cystic papillary tumor that was classified as a serous papillary cystadenoma, ovarian type, of borderline malignancy, with focal transition into invasive cancer. This appears to be the ninth reported case of testicular tumors of the serous or mucinous ovarian type and the first reported case with development of a circumscribed carcinoma from serous cystadenoma of borderline malignancy.