Testicular Tumours: Polyembryoma

Polyembryoma is an exceptionally rare gonadal neoplasm. Polyembryoma may be present as a component in a mixed germ cell tumour.
It has been reported that polyembryoma may present grossly as a beefy mass in the testis.
These neoplasms are composed entirely or predominantly of embryoid bodies, (characterized by a central germ disc, underlain by yolk sac epithelium, and with recapitulation of the amniotic cavity anteriorly and the yolk sac cavity posteriorly).
Foci of polyembryoma often have a prominent loose myxomatous mesenchyme in the background upon which the embryoid bodies are set. Large, well-circumscribed lobules of embryoid bodies surrounded by the prominent mesenchyme produce a rather typical low-power appearance in many cases.
Cysts may be prominent.
The embryoid bodies themselves often are not perfectly formed and appear fragmented, as if they are breaking down.

Abstracts:
Polyembrioma of the testis: case report following chemotherapy for non-Hodgkin's lymphoma. G Chir.2002 Mar;23(3):65-70.
Testicular tumours represent 2% of all male malignancies, mostly concerning young men (20-40 years old). The polyembryoma is one of the uncommonest lesions and just recently it has been identified as autonomous nosographic entity. The reported case is peculiar because the patient was older than the most ones described in the literature and the tumour arose after polychemotherapy for non Hodgkins' disease. The Authors analyse some aspects concerning etiology, pathology and clinical approach to such rare neoplasm.