Combination of a teratoma and embryonal carcinoma of the testis in SD IGS rats: a report of two cases.
Testicular tumors of germ cell origin are extremely rare in rats. We encountered 2 cases of teratoma and embryonal carcinoma in the testes of 8- and 10-week-old Sprague-Dawley IGS rats. A unilateral tumor mass with bilateral testicular atrophy was observed macroscopically in both cases. Microscopic examination revealed that the tumor mass had characteristic features of a teratoma and was composed of several types of differentiated cells and tissues at various stages of maturation. Embryonal carcinoma tissue, composed of undifferentiated cells with an embryonic and anaplastic appearance, was observed within the tumor mass. In addition, foci of intratubular teratomas and embryonal carcinomas were observed in the testis on the side without any obvious mass. No obvious germ cells were observed in the seminiferous tubules in the remnant nontumorous area. Furthermore, intratubular transition of cells was observed from the embryonal carcinoma tissue to the squamous epithelium. This finding indicates that an embryonal carcinoma differentiates toward a teratoma even at a very early stage of development of the germ cell tumor.
Sawaki
M
M
Chemicals Evaluation and Research Institute, Hita, Japan. sawaki-masakuni@fat.coara.or.jp
Shinoda
K
K
Hoshuyama
S
S
Kato
F
F
Yamasaki
K
K
D000818:Animals; D018236:Carcinoma, Embryonal / Q000473:pathology / Q000662:veterinary*; D008297:Male; D009378:Neoplasms, Multiple Primary / Q000473:pathology / Q000662:veterinary*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012376:Rodent Diseases / Q000473:pathology*; D013724:Teratoma / Q000473:pathology / Q000662:veterinary*; D013736:Testicular Neoplasms / Q000473:pathology / Q000662:veterinary*