Ovarian fibroma is the most common solid benign tumor of the ovary, belonging to the sex cord-stromal tumor group. It consists of spindle cell fibrous stroma proliferation. On imaging, it appears as a solid, hypoechoic/hypointense mass — marked T2 hypointensity is characteristic of fibrous tissue. Enhancement is poor or delayed. Association with Meigs syndrome (ascites + pleural effusion) is a classic and important clinical relationship. Calcification may be present. Generally unilateral and well-defined. No malignant potential (except cellular fibroma). Treatment is surgical excision; even in the presence of Meigs syndrome, ascites and pleural effusion completely resolve after surgery.
Age Range
40-70
Peak Age
55
Gender
Female predominant
Prevalence
Uncommon
Ovarian fibroma originates from fibroblast/myofibroblast cells of the ovarian stroma. It is characterized by dense collagen fiber accumulation — this fibrous structure directly determines the imaging features. The low water content and tight packing of collagen fibers creates marked T2 hypointensity (short T2 relaxation). For the same reason, it appears hypoechoic on US and soft tissue density on CT. Fibrous tissue vascularity is low — enhancement is poor or delayed because contrast agent slowly diffuses into the dense collagen matrix. Meigs syndrome mechanism: fluid transudation from the tumor surface into the peritoneal cavity (venous/lymphatic drainage impairment) → ascites → pleural effusion through diaphragmatic lymphatic channels. When the tumor is removed, the fluid source is eliminated and effusions resolve. Calcification develops due to degenerative changes and dystrophic calcification.
Solid ovarian mass showing signal intensity similar to or lower than skeletal muscle on T2W. This marked T2 hypointensity is pathognomonic for fibrous tissue and is the most valuable finding for differentiating ovarian fibroma from other solid ovarian masses (granulosa cell tumor, Brenner tumor, thecoma, metastasis). Granulosa cell tumor and thecoma show intermediate-to-hyperintense T2, while metastasis shows variable signal.
Homogeneous, hypoechoic solid lesion. Well-defined, oval or round shape. Cystic component is generally absent (unless degeneration). Posterior acoustic shadowing is seen when calcification is present. Central degeneration (edema, cystic change) in large fibromas can create heterogeneity.
Report Sentence
A ___ x ___ mm well-defined, homogeneous hypoechoic solid lesion is seen in the right/left ovary, consistent with ovarian fibroma.
Avascular or minimal vascularity on Doppler. Intratumoral vascular flow is absent or very low intensity. Peripheral capsular vascularity may be seen. Prominent intratumoral vascularity is expected in malignant solid tumors (granulosa cell tumor, carcinoma).
Report Sentence
No significant intratumoral vascularity is detected in the solid lesion on Doppler examination.
Markedly hypointense solid mass on T2W — signal intensity similar to or lower than skeletal muscle. Homogeneous signal. T2 hyperintense areas may be seen in large fibromas due to central edema/degeneration. T2 hypointensity of fibrous tissue is the most valuable MRI finding for differentiating ovarian fibroma from other solid ovarian masses.
Report Sentence
A markedly hypointense solid mass measuring ___ x ___ mm with signal intensity similar to skeletal muscle is seen in the right/left ovary on T2W; consistent with ovarian fibroma.
Intermediate-to-hypointense signal on T1W. Isointense or slightly hypointense to muscle. No hyperintensity (unless hemorrhage). Homogeneous signal is consistent with benign fibrous structure.
Report Sentence
The solid lesion shows signal isointense to muscle on T1W.
Well-defined solid mass of soft tissue density (40-60 HU) on CT. Enhancement is poor or delayed — minimal in arterial phase, may show mild increase in delayed phase. Calcification may be peripheral or central. Meigs syndrome should be considered in the presence of ascites and pleural effusion.
Report Sentence
A ___ x ___ mm solid mass of soft tissue density with poor enhancement is seen in the right/left ovary; Meigs syndrome should be considered in the presence of ascites and/or pleural effusion.
Calcification foci may be seen within the solid mass on non-contrast CT — central amorphous, peripheral rim, or coarse punctate pattern. Calcification presence supports chronic/degenerative process and strongly suggests benign character. Extensive calcification can create a densely calcified appearance covering the entire mass.
Report Sentence
Calcification foci in ___ pattern are seen within the solid mass.
Criteria
Entirely fibrous composition, homogeneous. Mitotic activity <4/10 HPF. Generally <10 cm.
Distinct Features
Homogeneously markedly T2 hypointense. No cystic component. Minimal enhancement. No malignant potential.
Criteria
Increased cellularity but mitotic activity <4/10 HPF and no atypia. Not at fibrosarcoma threshold.
Distinct Features
Slightly higher T2 signal than classic fibroma (increased cellularity = increased water). Enhancement may be relatively more. Recurrence risk slightly increased — complete excision is important.
Criteria
Ovarian fibroma + ascites + pleural effusion (usually right-sided). Fibroma size usually >10 cm. Syndrome completely resolves after surgery.
Distinct Features
Presence of ascites and pleural effusion may raise malignancy suspicion — but T2 hypointensity and poor enhancement of solid mass support benign fibroma diagnosis. CA-125 may be mildly elevated (due to ascites, not malignancy).
Distinguishing Feature
Thecoma appears slightly more hyperintense than fibroma on T2 (higher water/lipid content). Shows hormonal activity (estrogen → endometrial thickening). Fibroma does not produce hormones and is more markedly T2 hypointense.
Distinguishing Feature
Granulosa cell tumor shows solid-cystic mixed structure, intermediate-to-hyperintense T2 signal, prominent enhancement, and hormonal activity (estrogen/inhibin). Fibroma is entirely solid, T2 hypointense, and hormonally inactive.
Distinguishing Feature
Metastasis (Krukenberg) is usually bilateral, shows heterogeneous signal, intense enhancement, and history of known primary malignancy. Fibroma is unilateral, homogeneously T2 hypointense, poor enhancement, and no malignancy history.
Urgency
routineManagement
surgicalBiopsy
Not NeededFollow-up
12-monthOvarian fibroma is a benign lesion. Annual follow-up may be sufficient for small (<5 cm), asymptomatic fibromas. Surgical excision (laparoscopic cystectomy or oophorectomy) is recommended for large or symptomatic lesions. In the presence of Meigs syndrome, ascites and pleural effusion completely resolve after surgery — this is diagnostic confirmation. Complete excision and closer follow-up are needed for cellular fibroma. Elevated CA-125 due to Meigs syndrome may cause malignancy misdiagnosis — imaging features are distinguishing.
Ovarian fibroma is a benign tumor and surgical excision is curative. Meigs syndrome (ascites + pleural effusion) may accompany and resolves after tumor removal. May mimic malignancy (solid mass + ascites), but imaging features (T2 hypointensity) aid in diagnosis.