Testicular germ cell
neoplasia, a disease predominantly of young men, is, for unknown reasons, increasing in incidence.
Cryptorchidism, a prior
testicular germ cell tumor, a family history of testicular
germ cell tumors, and somatosexual ambiguity syndromes remain well-established risk factors. Intratubular germ cell
neoplasia of the unclassified type represents the common precursor to the great majority of testicular
germ cell tumors, and its identification in testicular biopsies reliably identifies those patients who will often progress to an invasive lesion.
Seminoma appears to represent the invasive derivative of intra-tubular germ cell of
neoplasia of the unclassified type; problematic variants include
seminomas with tubular, granulomatous, and edematous patterns. Spermatocytic
seminoma is an essentially nonmetastasizing
neoplasm unless complicated by the rare development of a sarcomatous component.
Embryonal carcinomas usually occur admixed with other
germ cell tumor types. The combination of positivity for
placental alkaline phosphatase and negativity for
epithelial membrane antigen can assist in the distinction of
embryonal carcinomas from somatic
carcinomas. The treatment of clinical stage I patients with
nonseminomatous germ cell tumor with "surveillance only" may be contraindicated depending on features that include the proportion of
embryonal carcinoma and the presence of lymphovascular invasion in the
orchiectomy specimen. It is important to be aware that pure, mature
teratomas in postpubertal patients may be associated with
metastases of teratomatous or nonteratomatous type
Yolk sac tumor is characterized by numerous patterns including glandular, myxomatous, sarcomatoid, hepatoid, and parietal variants.
Choriocarcinomas classically have a biphasic pattern of syncytiotrophoblast and cytotrophoblast; trophoblastic proliferations lacking a biphasic pattern also occur but are difficult to classify unless this category is broadened. Mixed
germ cell tumors, consisting of two or more different elements, are quite common. The polyembryoma is a distinctive, well-organized form of mixed
germ cell tumor consisting of
embryonal carcinoma and
yolk sac tumor.