Primary testicular carcinomas are histologically classified as germ cell tumors and non-germ cell tumors. The germ cell tumors constitute about 95% of all the tumors, which are further classified as seminomatous [more common] and non-seminomatous germ cell tumors [NSGCT].
1. Seminomatous germ cell tumor
2. Non- seminomatous germ cell tumor [NSGCT]. This category includes:
a. Embryonal cell carcinoma,
b. Yolk sac tumor
c. Mature teratoma
d. Immature teratoma
e. Choriocarcinoma and
f. Endodermal sinus tumor.
The non-germ cell tumors include the Sertoli cell and the Leydig cell tumors.
The embryonal variety of NSGCT, which has been illustrated here has a rapid and bulky growth and metastasizes early. It is commonly seen in the 22-35 age group and the patients present with an enlarged scrotum and pain. High levels of alpha-fetoprotein and beta HCG tumor markers are noted. Ultrasound of the scrotum is a reliable modality to quickly confirm the clinical findings of an intratesticular mass distinguishing it from other extratesticular processes, objectively characterize a palpable testicular tumor or detect an occult testicular primary. Ultrasound can prove helpful in identifying retroperitoneal nodal metastases [although CT and MRI are more commonly performed for this purpose]. Ultrasound also allows for the regular monitoring of these patients while on treatment and after therapy to detect recurrences.
The gray-scale ultrasound features are not very specific for any particular kind of testicular malignancy, but the histological type can sometimes be hypothesized based on certain appearances. The embryonal carcinoma is seen on ultrasound as a large, irregular tumor with loss of the normal architectural contour of the testis. The mass has a heterogeneous appearance, predominantly hypoechoic. It may be seen to infiltrate the tunica albuginea with extension into the spermatic cord structures. Areas of necrosis are seen as cystic spaces within the tumor. Sometimes, areas of hemorrhage and calcification may also be noted as hyperechoic foci.
Color Doppler imaging has a complementary role in the evaluation of testicular tumors. Most of the time, testicular tumors [> 1.6 cm] are hypervascular and this finding can be especially useful if the tumors are isoechoic to the normal testis. Segmental infarction may appear similar to a tumor using gray scale imaging, however, color Doppler can aid in distinguishing it by demonstrating no flow in the infarcted area.