Case Presentation: We report a case of a microcystic stromal tumour in left ovary with diameter about 8 cm in a 54 years-old woman who underwent a oophorectomy. Macroscopically, the ovary showed thickened wall with brown gelatinous material in the luminal surface. Microscopically, a poorly defined tumour composed of mixture of polyclonal tumour cells arranged in solid nests with variable small cystic spaces which coalesced into some larger spaces with intervening dense fibrous stroma. The tumour was composed of small, cuboidal cells with pale granular eosinophilic cytoplasm and frequent cytoplasmic vacuolation. Nuclei were monomorphic, centrally located with inconspicuous nucleoli. Tumour cells showed strong diffuse nuclear and cytoplasmic staining for β-catenin and CD10, and nuclear staining for cyclin D1. Cytokeratin AE1/AE3, inhibin, calretinin and AFP were negative.   Conclusion: This report illustrates a typical case of microcystic stromal tumour of ovary with distinctive combined histologic and immunohistochemical features. Clinically, it is regarded as a benign neoplasm, however, given the rarity and limited resources, further studies are needed.  

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