Ovarian fibrothecoma

Ovarian fibrothecomas comprise tumours in the spectrum of ovarian sex cord / stromal tumours where there are components of both an ovarian fibroma and an ovarian thecoma. 

Epidemiology

Most occur in adult women, with ~66% in postmenopausal women. Although they account for ~1% of all ovarian tumours ⁵, they are the most common benign solid ovarian tumour. It represents <2% of paediatric ovarian tumours.

Clinical presentation

The thecoma component of a fibrothecoma can secrete oestrogen, and the patient may present with abnormal vaginal bleeding and endometrial hyperplasia.

Pathology

These tumours have a variable amount of both fibrous tissue (see ovarian fibroma) and thecal cells (see ovarian thecoma). 

Radiographic features

Ultrasound

They may be seen as a homogeneous hypoechoic mass with posterior acoustic shadowing, although in most cases the sonographic appearance is nonspecific.

CT

The vast majority (~80%) of ovarian fibrothecomas appear as solid masses with a delayed accumulation of contrast medium. On dynamic CT, there is an absence of arterial vessels and absence or slight early uptake of contrast enhancement ³. Calcification may be present and, as these tumours enlarge, myxoid or cystic degeneration may occur, resulting in a heterogeneous pattern ⁴.

MRI

Reported signal characteristics include ¹:

• T1: typically shows homogeneous low signal intensity

• T2

  • lesions show predominantly homogeneous low signal intensity (from fibrous components)

  • scattered high signal areas may be present, representing areas of cystic degeneration +/- oedema

Treatment and prognosis

Most cases are benign and surgical resection is curative.

Fibrothecomas are at risk for adnexal torsion, particularly with large tumours ⁴.As with pure ovarian fibromas, Meigs syndrome may complicate ~1% of cases.

Differential diagnosis 

Consider other forms of ovarian tumours (especially fibrous components such as ovarian fibroma).