Mature cystic teratoma with high proportion of solid thyroid tissue: a controversial case with unusual imaging findings

摘要

We describe a case of a mature cystic teratoma of the ovary with high proportion of solid thyroid tissue (< 50% of the entire tumor) in a childbearing woman. The patient presented with non-specific abdominal bloating. Pelvic ultrasound and magnetic resonance imaging revealed a complex cystic-solid tumor confined to the left ovary with an anterior fat-containing locus compatible with mature cystic teratoma and a posterior predominantly solid component with low signal intensity on T2-weighted images that was histopatologically diagnosed as benign thyroid tissue. Thyroglobulin levels were in normal range. Although thyroid tissue is present in up to 20% of mature cystic teratomas, with exception of struma ovarii, it is not usually macroscopically nor radiologically identified. The differential diagnosis should include T2-hypointense adnexal lesions associated with mature cystic teratoma, malignant transformation of mature teratoma, and immature teratoma. Keywords: Urogenital neoplasms, Ovary, Teratoma, Thyroid gland, Magnetic Resonance ImagingCASE REPORTA routine ultrasound (US) examination revealed a complex cystic-solid left adnexal tumor in a 37-year-old woman complaining of diffuse abdominal bloating. The patient was admitted in our institution for further investigation. Her personal and family medical histories were unremarkable. On vaginal bimanual examination, an 80mm hard-elastic, mobile and painless mass was detected in the left adnexal area. The remainder of the physical examination was unremarkable. Routine laboratory data, thyroglobulin, and cancer antigen 125 (CA-125) were in the normal range.Imaging findingsPelvic transabdominal and transvaginal ultrasounds were performed and revealed a complex cystic-solid left adnexal tumor measuring approximately 85 mm × 60 × 60mm. The tumor had a larger cystic locus containing multiple thin, echogenic bands and a densely echogenic tubercle suggestive of a Rokitansky nodule (Fig. 1A), associated with a posterior solid echogenic mass with a small peripheral cystic area (Fig. 1B). The uterus and the right ovary were unremarkable. Open in a separate windowFigure 1 A 37-year-old woman with mature cystic teratoma of the left ovary with high proportion of thyroid tissue.Pelvic transvaginal ultrasound with a 10-MHz endocavitary probe.FINDINGS: A complex cystic-solid tumor was detected in the left adnexal area. The tumor had a larger cystic locus containing multiple thin and echogenic bands (white arrows; 1A), and a densely echogenic tubercle suggestive of Rokitansky nodule (white-bordered arrow; 1B). The cystic locus was associated with a posterior solid echogenic mass (thin white arrow; 1C) that contained a small peripheral cystic area (white asterisks; 1C).