Ovarian fibroma

Last revised by Dr Calum Worsley on 08 Apr 2022

Ovarian fibromas are a benign ovarian tumor of sex cord/stromal origin. Although fibromas account for ~4% of all ovarian neoplasms, they are the most common sex cord ovarian tumor.

Fibromas occur at all ages but are most frequently seen in middle-aged women.

Fibromas are generally asymptomatic and are often detected at palpation during a routine gynecologic examination. Tumors can reach a large size at presentation.

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.

They are associated with ascites in 40% of cases and with pleural effusions in a small percentage of cases. 

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.

Fibromas usually manifest as diffuse, slightly hypoattenuating masses with poor, very slow contrast enhancement. Calcification and bilaterality are both uncommon.

  • T1: fibromas usually demonstrate a homogeneous low signal intensity 
  • T2
    • fibromas 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 also considered a characteristic feature
  • DWI: hypointense
  • T1 C+ (Gd): usually shows heterogeneous enhancement 5

Ovarian fibromas are categorized as O-RADS MRI 2 2.

Ovarian fibromas are almost always benign 3.

General imaging differential considerations include:

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Cases and figures

  • Figure 1: gross pathology - ovarian fibroma
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  • Case 1
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  • Fig 2: macroscopic specimen
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  • Case 2
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  • Case 3: bilateral ovarian fibromata
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  • Case 4
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  • Case 5
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  • Case 6
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  • Case 7
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