An immunohistochemical study of primary ovarian sarcoma. An evaluation of nine tumors.

Nine cases of primary ovarian sarcoma were studied with a panel of 10 antibodies by using the avidin-biotin-complex immunoperoxidase technique. Original diagnoses included five mixed müllerian tumors (MMT) homologous type, two MMT heterologous type, and two pure sarcomas (PS). Cytokeratin immunoreactivity was observed in epithelial components of all MMTs, but was not observed in PS. Two tumors originally classified as MMT also showed cytokeratin positivity in spindle-cell components. All the PSs and the spindle-cell components in six of seven MMTs showed positive staining for vimentin. Positive staining for desmin and myoglobin was found in one MMT in which cells with cytoplasmic cross-striations were identified on hematoxylin and eosin sections. However, less differentiated rhabdomyoblastic cells also stained for desmin and myoglobin, facilitating their recognition. Immunoreactivity for epithelial membrane antigen was noted in well-differentiated epithelial components of six MMT cases. One case stained with antibodies to carcinoembryonic antigen, four with S-100 protein, five with alpha-1-antitrypsin, and four with muramidase. No staining of stromal hyaline droplets was observed with any antibodies. Because of the immunohistochemical staining pattern, two of the original diagnoses were changed. Application of immunohistochemistry to spindle tumors of ovary is discussed.