Ovarian thecoma

Ovarian thecomas are benign ovarian tumours of sex cord / stromal (mesenchymal) origin. They are thought to account for approximately 0.5-1% of all ovarian tumours. As ovarian thecomas secrete oestrogen, they are described as functional ovarian tumours.

They typically present in older women with over 80% showing in the postmenopausal period 2,5

Clinical manifestations of thecomas are similar to those of granulosa cell tumours, 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 tumour.

The tumour 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 5:

  • 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

On gross examination, they appear as solid masses of varying sizes. Cystic changes may occasionally be seen.  

Associations
Ultrasound

Initial imaging modality of choice. While sonographic features are generally non-specific 2, 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 oedema and cystic degeneration), but may be variable 
    • may mimic more common malignant ovarian tumours
  • IP/OP: intratumoral lipid may give a chemical shift artefact 3
  • T1 C+ (Gd)
    • the degree of contrast enhancement varies with the amount of fibrous tissue within the tumour
    • 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 tumour 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.

Thecomas are almost always benign and have low malignant potential, although there have been isolated reports of malignant thecomas.

  • fibroma

    • low signal on T2 given the fibroid content 

    • less enhancement 


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Article Information

rID: 13163
Section: Pathology
Synonyms or Alternate Spellings:
  • Thecoma of the ovary
  • Thecoma of ovary

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