Expanding the morphological spectrum of ovarian microcystic stromal tumour

To expand the morphological spectrum of ovarian microcystic stromal tumour, a rare neoplasm considered to have a relatively constant morphology with microcysts, solid cellular regions and hyalinised fibrous stroma.

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). The tumours had variant morphology (diffuse, nested and corded arrangements in three cases, including one with spindle cell elements; nested, corded and tubular in the other). A CTNNB1 point mutation in exon 3 (c.98C>G,p.S33C; c.100G>A,p.G34R; c.97T>G,p.S33A) was present in the three cases with material available for testing.

We feel that the cases we report are related to microcystic stromal tumour but with variant morphology; as such, the morphological spectrum of ovarian microcystic stromal tumour is broader than hitherto reported.