We identified 109
testicular tumors, including pure and mixed
germ cell tumors and
sex cord-stromal tumors, and conducted immunohistochemical staining for CDX2, DOG1, and GATA3 to address the potential utility of these readily available and commonly used markers in the evaluation of
testicular tumors. Their expression has not been previously thoroughly examined in testicular
germ cell tumors. The distribution, percentage, and intensity of positivity were assessed. CDX2 was positive in all
yolk sac tumors, 25% of
choriocarcinomas, 9% of
seminomas, and 4% of
embryonal carcinomas (sensitivity for
yolk sac tumor, 100%; specificity, 89% [
teratomas excluded]). CDX2 also stained glandular components within
teratomas and identified inconspicuous
yolk sac tumor components in 3 cases previously diagnosed as pure
embryonal carcinoma. GATA3 was positive in all
choriocarcinomas (sensitivity, 100%). Weak GATA3 immunostaining was also seen in 12% of
yolk sac tumors and 2 of 2
primitive neuroectodermal tumors. DOG1 was negative in all
tumors, but stained spermatocytes and spermatids and the
luminal borders of the epididymis and rete testis of nonneoplastic testis. We conclude that CDX2 is a sensitive and relatively specific marker for
yolk sac tumor among the nonteratomatous
germ cell tumors. It may serve to screen for
yolk sac tumor components often overlooked on
hematoxylin and
eosin-stained slides. GATA3 is helpful in the recognition of trophoblastic cells, especially of intermediate type. DOG1 is a sensitive marker for spermatocytes and needs to be further studied for its significance.