A Case of Struma Ovarii Diagnosed by Cytology during Laparoscopic Surgery

We report a case of pure struma ovarii tumor diagnosed by cytology during laparoscopic surgery. The patient was a 34-year-old Japanese woman, gravida 1, para 1, who had the left adnexal mass, and was pre-operatively diagnosed as left ovarian endometriotic cyst or mature cystic teratoma by magnetic resonance imaging findings. She underwent laparoscopy, and the content of the left ovarian cystic tumor was found to be yellow gelatinous material, suggesting mature cystic teratoma. The imprint cytology of the tumor showed benign glandular pattern, suggesting struma ovarii. Histopathological findings led us to the diagnosis of pure struma ovarii with positive reactions for thyroglobulin and thyroid transcription factor-1. No metastases or disseminated lesions were detected. The patient has no recurrent signs 7 months after the operation.