Mixed Seminoma and Malignant Teratoma of Testis
This was a surgical specimen from a 41 year old man who had a 14 month history of slow painless testicul enlargement.
The testis has been bisected longitudinally. The distal end of the spermatic cord is attached. The testis is greatly enlarged; before cutting the specimen measured 9 x 6 x 5 cm and weighed 225 grams. The cut surface shows complete replacement of the normal testicular tissue by a solid tumour containing occasional small cysts up to 3 mm in diameter, areas of pale yellow necrosis, focal fibrosis and patchy congestion and haemorrhage. There is no evidence of tumour invasion of the tunica or cord, although the latter is thickened by oedema and haemorrhage. A diagnosis of mixed seminoma and malignant teratoma was made by histological examination of the tumour.
Teratomas of the testis may occur at any age. They make up about 10% of adult testicular tumours. Testicular teratomas may be regarded as more differentiated versions of embroyonal carcinoma which have along the lines of all three embryonic cell layers, i.e., ectoderm, endoderm and mesoderm. Histologically teratomas may contain tissues of both mature and immature (or embyronic) type. Thus they are classified as either mature (eg, benign cystic teratoma of the ovary) or immature. Immature teratomas contain embryonic tissues such as neuroblasts, mesenchyme and embryonic cartilage, but may also contain foci of mature tissue. These tumours are malignant. In adult males, apparently mature teratomas are unusual and on careful examination often contain small foci of immature teratoma. They are likely to behave as malignant neoplasms. Benign testicular teratomas are more likely to occur in infants and children than in adults. About 90% of testicular tumours are mixed tumours, ie: they contain two or more types of testicular tumour. Common mixed tumours are teratoma and embryonal carcinoma, or seminoma combined with teratoma or embryonal carcinoma.