Seminomas often remain confined to the testis for long periods and may reach considerable size before diagnosis. Metastases most commonly are encountered in the iliac and paraaortic lymph nodes, particularly in the upper lumbar region. Hematogenous metastases occur late in the course of the disease.
Nonseminomatous germ cell neoplasms tend to metastasize earlier, by lymphatic as well as hematogenous routes. Hematogenous metastases are most common in the liver and lungs. Metastatic lesions may be identical to the primary testicular tumor or may contain elements of other germ cell tumors.
Fig. 18.9 Teratoma.Testicularteratomascontainmaturecellsfromendodermal,mesodermal,andectodermallines.(AtoD)Fourdifferentfieldsfromthesametumorspecimencontainneural(ectodermal)(A),glandular(endodermal)(B),cartilaginous(mesodermal)(C),andsquamousepithelial(D)elements.
Assay of tumor markers secreted by germ cell tumors is important in two ways; these markers (summarized in
Table 18.1 , along with salient clinical and morphologic features) are helpful diagnostically and very valuable in following the response of tumors to therapy after the diagnosis is established. HCG is always elevated in patients with choriocarcinoma and, as noted, may be minimally elevated in individuals with other germ cell tumors containing syncytiotrophoblastic cells. Increased AFP in the setting of a testicular neoplasm indicates a yolk sac tumor component. The levels of lactate dehydrogenase (LDH) correlate with the tumor burden.
The treatment of testicular germ cell neoplasms is a remarkable clinical success story. Although roughly 8000 new cases of testicular cancer occur in the United States yearly, fewer than 400 men are expected to die of the disease. Seminoma, which is extremely radiosensitive and tends to remain localized for long periods, has the best prognosis. More than 95% of patients with early-stage disease can be cured. Among nonseminomatous germ cell tumors, the histologic subtype does not influence the therapy. Approximately 90% of patients achieve complete remission with aggressive chemotherapy, and most are cured. The exception is choriocarcinoma, which is associated with a poorer prognosis. With all testicular tumors, recurrences, typically in the form of distant metastases, usually occur within the first 2 years after treatment.
Testicularneoplasmsarethemostcommoncauseofpainlesstesticularenlargement.Theyoccurwithincreasedfrequencyinassociationwithundescendedtestesandwithtesticulardysgenesis.
Germcellsarethesourceof95%oftesticulartumors,andtheremainderarisefromSertoliorLeydigcells.Germcelltumorsmaybecomposedofasingle“pure”histologicpattern(60%ofcases)ormixedpatterns(40%).
Themostcommonhistologicpatternsofgermcelltumorsareseminoma,embryonalcarcinoma,yolksactumor,choriocarcinoma,andteratoma.Mixedtumorscontainmorethanoneelement,mostcommonlyembryonalcarcinoma,teratoma,andyolksactumor.
Clinically,testiculargermcelltumorsaredividedintotwogroups:seminomasandnonseminomatoustumors.Seminomasremainconfinedtothetestisforalongtimeandspreadmainlytoparaaorticnodes;distantspreadisrare.Nonseminomatoustumorstendtospreadearlier,bybothlymphaticsandbloodvessels.
HCGisproducedbysyncytiotrophoblastsandisalwayselevatedinpatientswithchoriocarcinomasandthosewithseminomascontainingsyncytiotrophoblasts.AFPiselevatedwhenthereisayolksactumorcomponent.