Ovarian microcystic stromal tumors: clinical, radiological, and pathological studies of two cases

We observed two unusual cases of ovarian microcystic stromal tumors (MST). These two patients had no obvious clinical symptoms, and the imaging findings were separately diagnosed as cystic teratoma and ovarian malignant tumors. Significantly, during the operation, none of the pathologists considered the possibility of MST. The two cases showed similar morphological and immunophenotypic characteristics: some nests were made up of microcysts with round or oval shapes, and the cavity was bright and empty. In some areas, the cell nests of micro cysts were not obvious and were identified as solid cell nests. The tumor cells contained eosinophilic cytoplasms and neutral nuclei. Mitotic figures were rare. Immunohistochemistry indicated that the tumor cells were all positive for CD10, vimentin, WT1, and β-catenin, but negative for Cytokeratin, α-inhibin, CD99, ER, PR, S-100, EMA, CD56, CgA, Syn, Pax-8, Desmin, SMA, and calretinin. The Ki67 index was less than 5%. Based on the above characteristics, a diagnosis of ovarian MST was made after the operation. The final repeated CT scan revealed no recurrence during the post-surgical course. Here the clinical, radiological and pathological characteristics of these two cases diagnosed as ovarian MST are presented in order to help avoid future misdiagnosis and over-treatment.