Fibrothecoma, a benign mixed sex cord-stromal tumour of the ovary, is composed of fibroma and theca cells. On imaging, it typically presents as a well-circumscribed solid mass, showing low signal intensity on T2-weighted MRI.
Description
Fibrothecoma is a benign sex cord-stromal tumour that combines features of fibroma and thecoma. Predominantly observed in postmenopausal women, it accounts for approximately 4% of all ovarian neoplasms.
Pathogenesis
The exact pathogenesis of fibrothecoma is still unclear. It is believed that these tumours are derived from the stromal cells of the ovarian cortex which undergo abnormal proliferation and differentiate into fibrous and theca cells.
Subtypes
There are no recognised subtypes of fibrothecoma.
Epidemiology, Risk Factors & Associations
- Most commonly observed in postmenopausal women.
- No notable associations have been recognised.
Clinical Features
Clinical features of fibrothecoma can be non-specific, ranging from abdominal discomfort to a palpable abdominal mass. Rarely, patients may present with symptoms related to hormonal activity, such as postmenopausal bleeding.
Complications
There is a minimal risk of malignant transformation, and fibrothecomas are largely considered benign. The risk of malignant transformation is not well-established due to the rarity of these tumours.
Pathological Features
Histopathology
- Macroscopic: Characteristically demonstrates well-circumscribed, round, white, firm tumours with a smooth outer surface.
- Microscopic: Demonstrates a combination of fibrous tissue (fibroma component) and lipid-rich theca cells (theca component).
Serology
- No specific serologic markers are associated with fibrothecomas.
Biochemistry
- No specific biochemical markers are known.
Radiological Features
General Features
- Typically presents as a well-circumscribed solid ovarian mass. It has a homogeneous texture with areas of calcifications observed in about 10% of cases.
CT
- Non-contrast: Fibrothecomas appear as hypoattenuating masses.
- Contrast-enhanced: Minimal enhancement is observed after contrast administration.
MRI
- T1WI: Demonstrates low to intermediate signal intensity.
- T2WI: Typically shows low signal intensity.
- T1 C+: Minimal enhancement is observed after contrast administration.
- DWI/ADC: No diffusion restriction is typically observed.
US
- B-mode: Presents as a solid, hypoechoic mass with well-defined margins.
- Colour Doppler: Minimal vascularity is typically observed.
NM
- PET FDG: Fibrothecomas are typically not FDG avid.
Grading and Staging
There is no specific grading or staging system for fibrothecoma as it is a benign entity.
Diagnosis
The diagnosis of fibrothecoma is predominantly made on histopathological examination following surgical excision of the tumour.
Differential Diagnosis
- Ovarian Fibroma: Tends to be firmer and whiter on gross examination. On imaging, both fibroma and fibrothecoma may present similarly. Histological evaluation is definitive.
- Thecoma: Exclusively composed of theca cells. On MRI, thecomas typically exhibit a bright signal on T1W and a dark signal on T2W images.
- Leiomyoma: Commonly located within the uterus, and can often be differentiated based on its typical site and imaging characteristics.
- Ovarian Carcinoma: Tends to have a more aggressive appearance and behaviour, with complex solid and cystic morphologies often observed on imaging.
Management
The usual management of fibrothecoma involves surgical resection, particularly for symptomatic individuals or when there is uncertainty in diagnosis. Depending on the patient’s age, fertility requirements, and the size of the tumour, surgical approaches may range from ovarian cystectomy to salpingo-oophorectomy.