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.