Expanding the morphological spectrum of ovarian microcystic stromal tumour.

AIMS: 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.

METHODS AND RESULTS: 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.

CONCLUSIONS: 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.