Prepared by Susan J. Ackerman, MD, Lisa F. Baron, MD, and
Tara C. Noone, MD, Department of Radiology, Medical University of
South Carolina, Charleston, SC.
A 76-year-old woman presented with a pelvic mass on physical
examination. Her medical history was unremarkable. An ultrasound
examination was performed.
Ultrasound of the pelvis was performed with a 3-Mhz transducer.
A well-defined heterogeneous mass was noted in the right adnexa
measuring 4.7 * 5.0 * 3.5 cm (figure 1). The mass was primarily
hypoechoic with echogenic foci scattered throughout. Eccentrically
located within the mass was a 1.5-cm heterogeneous nodule with a
sonolucent center. Doppler evaluation showed arterial flow (figure
2). No ascities or adenopathy was noted. No normal right ovarian
tissue was seen. The left ovary was normal in appearance. The
uterus was absent surgically. Because of the possibility of
malignancy, the right adnexal mass was removed surgically and
pathologically proven to be struma ovarii.
Struma ovarii is a rare germ-cell tumor of the ovary, consisting
mainly of thyroid tissue. Ninety-five percent of these tumors are
benign. Five percent of these tumors contain a carcinoid component
considered malignant transformation.
Only 5% of these malignant tumors metastasize. Struma ovarii tumors
are generally asymptomatic and are usually discovered incidentally
during a routine physical examination. Seldom, patients may
complain of a palpable pelvic mass. However, in a few cases, these
tumors can secrete thyroid hormones and the patients present with
symptoms seen in hyperthyroidism such as thyroid enlargement and
Elevated cancer antigen 125 (CA-125) levels are rarely seen with
struma ovarii, usually in the setting of ascites.
In order to make the correct diagnosis, histologic examination of
the mass ovary must show thyroid follicles.
Immunohistochemical staining for thyroglobulin may be done in
For benign pure struma ovarii, surgical resection is usually
curative with complete resolution of the patient's symptoms.