On the Pathogenesis of Sclerosing Stromal Tumor of the Ovary: A Neoplasm in Transition

Sclerosing stromal tumor (SST) is a distinctive benign ovarian stromal neoplasm first reported in 1973. Although its initial description supports its characterization as an ovarian stromal tumor, its exact pathogenesis remains uncertain. It is usually hormonally inactive, but occasional tumors are estrogenic or androgenic, and virilization can occur during pregnancy. We report 11 cases of SST, 6 of which were associated with another type or other types of ovarian stromal tumor. In 4 of these, a transition from thecoma of either typical or luteinized type to SST was observed. Our index case was that of a 16-yr-old girl who had a typical thecoma that underwent involutional changes in an extensive subserosal portion of the tumor with conversion to SST. In our series, 3 cases of SST underwent transformation to ovarian myxoma, one of which also contained a component of thecoma. The active SST components stained for inhibin, steroidogenic factor 1, and alpha-smooth muscle actin, but were negative or occasionally weakly positive for desmin.