Testicular Tumours: Mixed Germ Cell Tumour

Mixed Germ Cell Tumour
Mixed germ cell tumours contain more than one germ cell component.
Of the nonseminomatous germ cell tumours, mixed germ cell tumours are much more common than any of the pure histologic forms and represent 32%–60% of all germ cell tumours.
Essentially, any admixture of the germ cell tumours as seen in pure form may be seen, one of the most common admixtures being embryonal carcinoma and teratoma (the old teratocarcinoma). Minor foci of yolk sac tumor are common, although it is usually overshadowed by other components, such as embryonal carcinoma. As is typical of embryonal carcinoma when seen in pure form, epithelium is often associated with syncytiotrophoblast giant cells when seen as part of a mixed germ cell tumour.
Although seminoma may be seen as part of a mixed germ cell tumour, in some cases one sees seminoma separate from a dominant mass of nonseminomatous mixed germ cell neoplasia, and in such cases it is probably truly multicentric neoplasia, although for sign-out purposes it is probably sufficient to consider the seminoma together with the other neoplastic components under the one designation of mixed germ cell tumour with the traditional rough quantitation of the various components in descending order of frequency.
Note: Embryonal carcinoma is the most common component and is often combined with one or more components of teratoma, seminoma, and yolk sac tumour.
The average age of presentation for patients with mixed germ cell tumours is 30 years.

Abstract:
Mixed testicular germ cell tumor in an adult with cryptorchidism and Down's syndrome. APMIS. 2007 Nov;115(11):1292-5.
We here present a case of mixed testicular germ cell tumor in an adult with cryptorchidism and Down's syndrome. A 20-year-old Japanese man with a mass in the left inguinal region underwent orchidectomy as a left testicular tumor was suspected. Histology showed a mixed germ-cell tumor with embryonal carcinoma and yolk sac tumor with syncytiotrophoblastic giant cells occurring in a cryptorchid testis. Chromosomal analysis of peripheral lymphocytes disclosed a karyotype of 47,XY,+21[20]. Our case provides further evidence that these three conditions-Down's syndrome, cryptorchidism and testicular germ cell tumor-may be closely associated. To our knowledge this is the first case of mixed germ cell tumor arising in a patient with Down's syndrome and cryptorchidism.