Objective Ultrasound features of granulosa cell tumors of the ovary are still poorly defined. The aim of this study is to widen current knowledge on the role of sonographic gray scale and pattern recognition in the characterization of these tumors and to compare the ultrasound characteristics of primary diagnosis and recurrences.

Methods Transvaginal ultrasound images of primary diagnosis or recurrences of histologically-confirmed granulosa cell tumors of the ovary were retrospectively retrieved from a dedicated database designed for the collection of clinical and ultrasound data from January 2001 to January 2019. All patients included were treated at San Raffaele and Santa Chiara Hospitals. Women with a concomitant diagnosis of another malignancy other than endometrial carcinoma were excluded from the study. All ultrasound images were described according to International Ovarian Tumor Analysis terminology and examined by experienced ultrasound examiners.

Results A total of 27 patients were included: 24 with adult and 3 with juvenile ovarian granulosa cell tumors. At primary diagnosis, mean ovarian mass size was 103.8 mm (range 30–200). On ultrasound evaluation at primary diagnosis, 12 patients presented with a multilocular solid lesion (48%), 9 with a solid lesion (36%), and 4 with a multilocular lesion(16%). The echogenicity of the cyst was low level or anechoic, mixed, or hemorrhagic in 56.3%, 31.2%, and 12.5% of cases, respectively. Most tumors (45.1%), including first diagnosis and relapses, had a moderate to high color score on doppler evaluation.

Conclusions Our study showed that sonographic features and pattern recognition of relapses were comparable to those of tumors at primary diagnosis. In order to highlight the importance of transvaginal ultrasound evaluation during follow-up, further studies based on a standardized ultrasound characterization of ovarian masses are recommended.