We report four ovarian neoplasms in patients aged 45, 56, 61 and 71 years with the characteristic immunophenotype of microcystic stromal tumour (diffuse nuclear positivity with beta-catenin, cyclin D1 and WT1; diffuse cytoplasmic positivity with CD10; negative inhibin, calretinin, oestrogen receptor and progesterone receptor).
Since our first description of the microcystic stromal tumor (MST) of the ovary, a rare and distinctive neoplasm with a definitional, usually striking microcystic pattern and a CD10+/vimentin+/inhibin-/calretinin- immunophenotype, 3 examples with β-catenin nuclear localization, and CTNNB1 mutation have been reported.
The results of this study strongly suggest that dysregulation of the Wnt/β-catenin pathway plays a fundamental role in the pathogenesis of ovarian MCST.