Signet ring stromal cell tumor revisited and related signet ring cell lesions of the ovary

Summary In this article, we revisit the first reported case of ovarian signet ring stromal cell tumor (SRSCT) using modern immunohistochemical techniques and compare it to a case of signet ring cell transformation of lutein cells in an ovarian stromal tumor having components of luteinized thecoma and sclerosing stromal tumor. We introduce a new classification of signet ring stromal cell lesions of the ovary that serves as a framework to distinguish pathogenetically distinct ovarian stromal lesions that may be confused with cases of true SRSCT. The SRSCT in our first case most likely arose directly from the ovarian stroma without an identifiable precursor neoplasm. In our second case, the association of the signet ring cells with lutein cells and the positive staining of the signet ring cells for inhibin and steroidogenic factor 1 confirm that in some instances signet ring cells are derived from lutein cells.