Meningeal nodules in teratoma of the testis.

A case of a 52-year-old man with a mature adult teratoma is reported. Beside histologically mature tissues, this teratoma contained large areas of a meningiomatous proliferation in close proximity of a peripheral nerve and glial tissue. These meningiomatous proliferations were mostly seen in the peripheral parts of the teratoma surrounding the rest of teratomatous elements and were immunohistochemically EMA-positive and S-100 protein- and cytokeratin-negative. Identical meningothelial proliferations are well known in the skin and adjacent soft tissues of the scalp, where they have variously been called sequestrated meningoceles, meningeal hamartoma, cutaneous meningiomas, rudimentary meningocele, hamartoma of the scalp with ectopic meningothelial elements, or cutaneous heterotopic meningeal nodules.