Cytokeratin and CD30 expression in dysgerminoma

Dysgerminoma is a malignant germ cell tumor of the ovary that shares morphological, immunophenotypic, and genetic features with its testicular counterpart, seminoma. Recent evidence supports the hypothesis that seminoma can differentiate into non-seminomatous germ cell tumor types. The progression of these tumors can be measured by their acquisition of the potential to express cytokeratin intermediate filaments, a characteristic specific to epithelial differentiation. Although testicular seminomas have been widely investigated, little is known about cytokeratin or E-cadherin expression in dysgerminomas. We investigated 26 formalin-fixed, paraffin-embedded ovarian dysgerminomas with immunohistochemical stains for CAM5.2, AE1/AE3, epithelial membrane antigen, cytokeratin 7, cytokeratin 20, high-molecular-weight keratin, and E-cadherin. In addition, we investigated the CD30 and vimentin immunoreactivity of these tumors. Immunoreactivity for CAM5.2 and for AE1/AE3 was present in more than 10% of neoplastic cells in 5 (19.2%) of 26 cases and in 2 (7.7%) of 26 cases, respectively. Cytokeratin 7 showed only focal positivity and never showed positive staining in greater than 10% of dysgerminoma cells. E-cadherin staining was positive in 2 cases showing weak membranous immunostaining in more than 10% of cells. Vimentin immunoreactivity was observed in only 2 dysgerminomas, both of which had less than 10% of the neoplastic cells staining. Cytokeratin 20, epithelial membrane antigen, high-molecular-weight keratin, and CD30 were consistently negative in all cases. Our study demonstrates that cytokeratin expression in dysgerminomas is not unusual and is consistent with the hypothesis that dysgerminomas have the capacity to differentiate along epithelial lines. Furthermore, the immunohistochemical staining patterns for cytokeratins, E-cadherin, and CD30 in dysgerminomas need to be considered when assessing differential diagnoses in difficult cases of primary ovarian tumors.

Chromosome 12p abnormalities in dysgerminoma of the ovary: a FISH analysis

Dysgerminoma is the most common malignant ovarian germ cell tumor and shares histological and immunophenotypical features with its testicular counterpart, seminoma. Chromosome 12p abnormalities are genetic hallmarks of testicular seminomas. Little is known about these genetic changes in dysgerminoma. We performed dual color fluorescence in situ hybridization (FISH) analyses with a centromeric alpha-satellite probe for chromosome 12 and a subtelomeric probe for 12p on paraffin-embedded tissue sections from 21 dysgerminomas and two gonadoblastomas. Chromosome 12p abnormalities were detected in 81% of dysgerminomas. In all, 57% of cases had only isochromosome 12p and 5% had only 12p overrepresentation. In all, 19% had both isochrome 12p and 12p overrepresentation. Gonadoblastomas were negative for isochromosome 12p or 12p overrepresentation. Chromosome 12p abnormalities are common in dysgerminoma of the ovary. FISH analyses for chromosome 12p abnormalities may be a useful diagnostic adjunct for confirming the diagnosis of dysgerminoma and for distinguishing it from nongerm cell malignancies that enter into the differential diagnosis.

Expression of CD117 (c-kit) receptor in dysgerminoma of the ovary: diagnostic and therapeutic implications

The proto-oncogene c-kit encodes a tyrosine kinase receptor, c-kit (CD117), which has been implicated in the development of a number of human malignancies. While the preferential expression of this protein has been well documented in testicular seminomas, there is little data concerning its expression in dysgerminomas of the ovary. We examined the expression of c-kit in 30 cases of ovarian dysgerminomas using immunohistohemical staining with a polyclonal anti-CD117 antibody. Staining was graded in a semiquantitative manner as follows: negative (no staining), 1+(1-10% staining), 2+(10-29% staining), 3+(30-50% staining), or 4+ (>50% staining). Of the 30 cases examined, 26 (87%) demonstrated immunoreactivity for CD117. In total, 10 (33%) demonstrated 4+ staining; 9 (30%) demonstrated 3+staining; 3 (10%) demonstrated 2+staining; 4 (13%) demonstrated 1+staining; and 4 (13%) demonstrated no staining. In conclusion, CD117 immunoreactivity was detected in 87% of ovarian dysgerminomas, a finding that correlates with previously reported frequencies of CD117 expression in seminomas (78-100%). Thus, antibodies to c-kit may be a useful diagnostic marker for ovarian dysgerminoma. Although the prognosis of patients with dysgerminoma is generally good, this receptor could potentially serve as a target for site-specific immunotherapy as an alternative and/or complement to conventional treatment options.

OCT4: a novel biomarker for dysgerminoma of the ovary

The prognosis and therapy for dysgerminomas are different from those of other ovarian tumor types, making accurate diagnosis imperative for patient care. OCT4 (POU5F1) is a transcription factor involved in the regulation of pluripotency during embryonic development. It can be detected in both pluripotent cells and other early germ cells. This study examines the expression of OCT4 in both dysgerminoma and nondysgerminomatous neoplasms involving the ovary. Formalin-fixed, paraffin-embedded cell blocks of 33 cases of dysgerminoma including 2 cases of gonadoblastoma associated with dysgerminoma and 3 cases of metastatic dysgerminoma, and 111 cases of nondysgerminomatous neoplasms involving the ovary were stained using the antibody against OCT4. All cases of dysgerminomas and gonadoblastomas were positive for OCT4 with strong nuclear staining. More than 90% of dysgerminoma cells in each case showed diffuse strong nuclear staining. In addition, 3 metastatic dysgerminomas also showed uniform strong nuclear staining. All nondysgerminomatous tumors (mature teratoma, 14; yolk sac tumor, 4; Sertoli-Leydig cell tumor, 15; granulosa cell tumor, 22; Brenner tumor, 3; carcinoid tumor, 4; struma ovarii, 2; fibroma, 5; thecoma, 1; serous adenocarcinoma, 5; endometrioid adenocarcinoma, 4; small cell carcinoma, 6; stromal sarcoma, 1; malignant lymphoma, 6; metastatic malignant melanoma, 1; metastatic carcinoid, 2; metastatic small cell carcinoma, 1; and metastatic lobular carcinoma of the breast, 1) were negative for OCT4, except for some cases of clear cell adenocarcinoma of the ovary. Four of 14 clear cell adenocarcinomas showed focal positive nuclear immunoreactivity for OCT4. OCT4 is a sensitive and relatively specific biomarker for the detection of dysgerminoma. It may also be useful in the diagnosis of gonadoblastoma, which contains similar cells and may be associated with dysgerminoma. OCT4 may aid in the detection of small foci of metastatic dygerminoma in extraovarian sites and may also help distinguish dysgerminoma from other primary and metastatic tumors of the ovary.