Ovarian fibromas are benign ovarian tumors of sex cord/stromal origin. Although fibromas account for ~4% of all ovarian neoplasms, they are the most common sex cord ovarian tumors.
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Epidemiology
Fibromas occur at all ages but are most frequently seen in middle-aged women.
Associations
They are associated with ascites in 40% of cases and with pleural effusions in a small percentage of cases.
Meigs syndrome: consists of ovarian fibroma with ascites and a pleural effusion
fibromas are seen in 75% of patients with Gorlin-Goltz (nevoid basal cell carcinoma) syndrome 1
Clinical presentation
Fibromas are generally asymptomatic and are often detected at palpation during a routine gynecologic examination. Tumors can reach a large size at presentation.
Pathology
The tumor belongs to the same histopathologic spectrum as an ovarian thecoma/ovarian fibrothecoma. Fibromas have no (or very few) thecal cells and no (or minimal) estrogen activity.
It is composed of spindle cells forming variable amounts of collagen. Sectioning of a fibroma typically reveals a chalky-white surface that has a whorled appearance, similar to that of a uterine fibroid. Areas of edema, occasionally with cyst formation, are also relatively common.
Radiographic features
Ultrasound
On ultrasound, fibromas most commonly manifest as solid, hypoechoic masses with ultrasound beam attenuation. As such, they may appear similar to a pedunculated subserosal uterine fibroid.
However, the sonographic appearance can be variable, and some tumors can rarely have cystic components.
CT
Fibromas usually manifest as diffuse, slightly hypoattenuating masses with poor, very slow contrast enhancement. Calcification and bilaterality are both uncommon.
MRI
T1: usually demonstrate homogeneous low signal intensity
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T2
appear as well-circumscribed masses with low signal intensity
may contain scattered hyperintense areas representing edema or cystic degeneration
a band of T2 hypointensity separating the tumor from the uterus on all imaging planes is considered a characteristic feature
DWI: hypointense
T1 C+ (Gd): usually shows heterogeneous enhancement 5
On dynamic contrast-enhanced MRI, enhancement of the fibromas and fibrothecomas is lower than that of myometrium and fibroids
Ovarian fibromas are categorized as O-RADS MRI 2 2.
Treatment and prognosis
Ovarian fibromas are almost always benign 3.
Complications
Differential diagnosis
General imaging differential considerations include:
large pedunculated subserosal uterine leiomyoma
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thecoma and fibrothecoma
tend to have brighter signal on T2 given edema and cystic degeneration
contrast-enhancement may be observed given the vascularization of the theca cells
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calcification more common
associated with another epithelial tumor in ipsilateral or contralateral ovary in some cases
may have cystic components
solid components show contrast enhancement