Abstract: Ovarian microcystic stromal tumor (MCST) is a rare tumor with unique morphological characteristics and immunophenotype. Its biological behavior tends to be benign. This case reported a patient with ovarian microcystic stromal tumor admitted to Peking Union Medical College Hospital in June 2018. After active surgical treatment, the patient is in a good general condition with no special discomfort and no signs of recurrence or metastasis after 18 months of follow-up. This paper discusses the clinicopathological features, immunophenotype and differential diagnosis of ovarian MCST，so as to provide information and reference for medical researchers and clinical workers. 

Key words: Microcystic interstitial tumor;, Ovarian neoplasms;, Pathology, clinical;, Diagnosis;, Diagnosis, differential, Case reports