ovarian thecoma
Ovarian thecomas are benign ovarian tumors of sex cord / stromal (mesenchymal) origin. They are thought to account for approximately 0.5-1% of all ovarian tumors. As ovarian thecomas secrete estrogen, they are described as functional ovarian tumors.
Epidemiology
They typically present in older women with over 80% showing in the postmenopausal period .
Clinical presentation
Clinical manifestations of thecomas are similar to those of granulosa cell tumors, with uterine bleeding predominating (~60% of cases).
Occurrences of hyperestrogenism secondary to a thecoma or fibrothecoma are less common than those secondary to a granulosa cell tumor.
Pathology
The tumor belongs to the same histopathologic spectrum as a fibroma/fibrothecoma. A typical thecoma consists of swollen lipid-laden stromal cells with a small component of fibroblasts. It can be divided into two main types :
- typical
- luteinised
- a thecoma containing steroid-type cells resembling luteinised theca and luteinised stromal cells are called a luteinised thecoma
- occurs in a younger age group than a typical thecoma
- ~50% oestrogenic
- ~40% non-functioning
- ~10% androgenic
- a thecoma containing steroid-type cells resembling luteinised theca and luteinised stromal cells are called a luteinised thecoma
On gross examination, they appear as solid masses of varying sizes. Cystic changes may occasionally be seen.
Associations
- most thecomas appear as a mixture of fibroma and thecoma components, so-called ovarian fibrothecoma
- more than 20% have concurrent endometrial carcinoma
Radiographic features
Ultrasound
Initial imaging modality of choice. While sonographic features are generally non-specific , a thecoma may manifest as:
- an echogenic mass with distal acoustic attenuation
- a well-defined hypoechoic mass, or
- an anechoic lesion with through-transmission
Secondary features of hyperestrogenism, such as endometrial thickening, also may be seen.
CT
Typically appear as unilateral, solid ovarian masses.
MRI
- T2
- usually hyperintense (often from edema and cystic degeneration), but may be variable
- may mimic more common malignant ovarian tumors
- IP/OP: intratumoral lipid may give a chemical shift artefact
- T1 C+ (Gd)
- the degree of contrast enhancement varies with the amount of fibrous tissue within the tumor
- while theca cells in the normal ovary are highly vascularized, the fibrous tissue is known for delayed weak enhancement at dynamic contrast-enhanced imaging
If the tumor has a significant fibroma component (i.e. fibrothecoma), the abundant fibrous tissue may produce predominantly low signal intensity on both T1 and T2 weighted sequences.
Secondary features of hyperestrogenism, such as endometrial thickening, also may again be seen.
Treatment and prognosis
Thecomas are almost always benign and have low malignant potential, although there have been isolated reports of malignant thecomas.
Differential diagnosis
-
- low signal on T2 given the fibroid content
- less enhancement
- adult granulosa cell tumor
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