The prognosis and
therapy for malignant ovarian
germ cell tumors including
embryonal carcinoma differ from those of other categories of ovarian
tumors, making accurate diagnosis imperative for patient care. Because of its rarity, the
protein markers and genomic alterations typifying primary ovarian
embryonal carcinoma have not been fully characterized. The present study aims to establish a set of sensitive and specific
protein markers useful for the diagnosis and delineation of ovarian
embryonal carcinoma. Chromosomal 12p anomalies were analyzed by dual-color fluorescence in situ hybridization. In a series of 6 ovarian mixed
germ cell tumors with a component of
embryonal carcinomas, OCT4, CD30, SOX2, and
glypican 3 expressions were analyzed immunohistochemically on
formalin-fixed
paraffin-embedded tissue specimens. The results were compared to 4 cases of mixed
germ cell tumor that were originally mistaken for
embryonal carcinoma. OCT4 marked the nuclei of 6 cases, among which 5 cases also showed
glypican 3 expression indicative of an admixed
yolk sac tumor component. SOX2 was positive in only 3 cases of
embryonal carcinoma. In 1 case of mixed
germ cell tumor containing
embryonal carcinoma, embryoid bodies from a component of polyembryoma were demonstrated to be both OCT4 and CD30 positive. Two cases originally classified as
embryonal carcinoma were OCT4 and CD30 negative and showed
glypican 3 positivity. They were reclassified as solid variant of
yolk sac tumor. Two other cases originally classified as
embryonal carcinoma were OCT4 positive and CD30 negative and were classified as
immature teratoma with neuroectodermal differentiation based on the immunohistochemical findings as well as morphologic features and were diagnosed as
immature teratoma. Chromosome 12p alterations were identified in 5 of 6 cases of
embryonal carcinomas. In summary, a panel of immunostains is more useful than a single
biomarker in the differential diagnosis of ovarian
germ cell tumors. Chromosome 12p fluorescence in situ hybridization combined with OCT4, CD30, and
glypican 3 immunostains is useful in confirming the diagnosis of ovarian
embryonal carcinoma.