·To investigate the clinicopathological features and prognosis of ovarian granulosa cell tumor (GCT) in children.

·The clinicopathologic and follow-up data of 8 patients with ovarian GCT in Shanghai Children's Hospital from June 2008 to June 2018 were collected and retrospectively studied to summarize the clinicopathological features and analyze the prognosis.

·The age of onset in this group ranged from 2 to 12 years with median age of 6.5 years. Two cases were adult granulosa cell tumor (AGCT) and six cases were juvenile granulosa cell tumor (JGCT). The first symptoms were abdominal pain or abdominal mass. Six patients were complicated with symptoms of precocious puberty, including 5 cases of true precocious puberty and 1 case of pseudo precocious puberty. The levels of peripheral blood sex hormones changed to varying degrees. Gross examination showed that the tumor masses ranged from 4 to 22 cm in the greatest dimension (average 12.8 cm). All of the 8 tumors were mixed solid-cystic in appearance. Under light microscope, AGCT showed obvious nuclear sulcus and microfollicular structure, containing eosinophilic substances, namely characteristic Call-Exner bodies. JGCT had follicular structures of different sizes, containing basophilic secretions. The inner layer of the follicular wall was composed of granular cells, which could be surrounded by follicular membrane cells. No Call-Exner bodies were found, and nuclear sulcus were rare. The results of immunohistochemistry showed that α-inhibin and CD99 were positive, and epithelial membrane antigen (EMA) were negative in all the cases. In 5 cases calretinin were positive, and in 5 cases cytokeratin (CK) were positive. Ki-67 proliferation index was 5%?50%. There were 3 estrogen receptor (ER) positive cases and 6 progesterone receptor (PR) positive cases. Forkhead transcription factor 2 (FOXL2) was highly expressed in 2 cases of AGCT and 6 cases of JGCT. SRY-box transcription factor 9 (SOX9) positive cells were scattered in 2 cases of AGCT and 3 cases of JGCT. All the cases were treated with standard surgery. Tumor rupture or metastasis was found in 5 cases, and ascites was suspiciously positive in 1 case. Eight children with ovarian GCT were followed up for 19?155 months, and all of them survived in good health.

·The clinical features of AGCT and JGCT in children's ovaries are similar and have typical histopathological features respectively. The selection of suitable immunohistochemical detection method is helpful for differential diagnosis of ovarian tumors in children. The prognosis of ovarian GCT in children is good even with tumor rupture after radical surgery.