AUTHOR AND EDITOR INFORMATION

Section 1 of 9  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• Mri
• Ultrasound
• Intervention
• Multimedia
• References

INTRODUCTION

Section 2 of 9  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• Mri
• Ultrasound
• Intervention
• Multimedia
• References

Background

Radiologists must be familiar with a variety of benign breast conditions to confidently distinguish malignant disease from benign disease. Fibroadenomas are benign tumors composed of stromal and epithelial elements. These tumors are commonly seen in young women. Multiple or complex fibroadenomas may indicate a slightly increased risk for breast cancer; the relative risk of patients with such fibroadenomas is approximately twice that of patients of similar age without fibroadenomas.

For excellent patient education resources, visit eMedicine's Cancer and Tumors Center and Women's Health Center. Also, see eMedicine's patient education articles Breast Cancer, Breast Lumps and Pain, and Breast Self-Exam.

Pathophysiology

Fibroadenomas are benign tumors that represent a hyperplastic or proliferative process in a single terminal ductal unit; their development is considered to be an aberration of normal development. The cause of these tumors is unknown. Approximately 10% of fibroadenomas disappear spontaneously each year, and most stop growing after they reach 2-3 cm.

Fibroadenomas may involute in postmenopausal women, and coarse calcifications may develop. Conversely, fibroadenomas may grow rapidly during pregnancy, during hormone replacement therapy, or during immunosuppression, in which case they can simulate malignancy. In immunosuppressed patients, the etiology of multiple or growing fibroadenomas appears to be related to Epstein-Barr virus infection.

Fibroadenoma variants include juvenile fibroadenomas, occurring in female adolescents, and myxoid fibroadenomas, occurring in persons with Carney complex. Carney complex is an autosomal dominant neoplasia syndrome that includes skin and mucosal lesions, myxomas, and endocrine disorders.

Frequency

United States

Fibroadenomas are among the most common breast lesions, particularly in women younger than 40 years. Approximately 10-15% of fibroadenomas are multiple.

Mortality/Morbidity

Fibroadenomas are benign lesions and are not considered to have malignant potential. However, because they contain epithelium, a risk of neoplasia exists, as in other locations in the breast. The risk of a breast carcinoma occurring within a fibroadenoma is about 3%.

• Carcinoma is twice as likely to occur in women who have previously undergone excision of a fibroadenoma.
• The relative risk of carcinoma is increased in women who have fibroadenomas associated with cysts, sclerosing adenosis, calcifications, or papillary apocrine change.
• Juvenile fibroadenomas, otherwise called giant fibroadenomas, are rapidly growing benign tumors that occur in female adolescents. These tumors are cured with excision.

Race

No racial predilection is noted.

Age

Fibroadenomas may occur in girls and women of any age during their reproductive years. After menopause, the tumors often regress. Fibroadenomas rarely appear in older women; therefore, any new solid lesion in an older woman should be considered malignant until proven otherwise. Cancers are the most common solid masses in postmenopausal women.

The prevalence of fibroadenomas is approximately 8-10% in women older than 40 years. Fibroadenomas are the second most common solid tumor after breast cancer and the most common benign tumor in women. In women younger than 30 years, fibroadenoma is the most commonly diagnosed breast tumor.

Fibroadenomas are common in younger women. Because women younger than 40 years are not ordinarily screened with imaging, detection by palpation is the most common method by which fibroadenomas are detected in women in this age group.

Anatomy

Fibroadenomas are tumors that may occur anywhere in the breast. These tumors are composed of both stromal and epithelial elements. Two kinds of breast stroma exist: intralobular stroma and interlobular stroma. Intralobular stroma contains lobules composed of 6-10 major ductal systems surrounded by a myxomatous stroma; it is from this stroma that fibroadenomas arise. Interlobular stroma is composed of dense fibroconnective tissue mixed with adipose and elastic tissue.

Clinical Details

On clinical examination, fibroadenomas are oval, freely mobile, rubbery masses that may be nonpalpable or palpable. Their size varies from smaller than 1 cm in diameter to as large as 15 cm in diameter in the giant forms. Most commonly, the tumors are removed surgically when they are 2-4 cm in diameter. In young women, the tumors are usually palpable. In older women, the tumors typically appear as a mass on mammograms and may be palpable or nonpalpable.

In approximately 50% of women who receive cyclosporine after renal transplantation, fibroadenomas develop, and these tumors are often multiple and bilateral. The size of fibroadenomas also can vary during the menstrual cycle and during pregnancy. During postmenopause, tumors regress and often develop calcifications. Cancer may arise in a fibroadenoma, occurring in about 2.9% of cases; an increase in size, a change or irregularity in the margin, the development of small pleomorphic calcifications, and the presence of cystic spaces all suggest a developing malignancy.

Preferred Examination

A patient's age determines the preferred imaging method. In general, ultrasonography (US) is preferred if a palpable mass is found, if a patient is younger than 30 years, or if the patient is pregnant. Mammography and US are both useful if the patient has a palpable mass, is older than 30 years, and is not pregnant.

In patients younger than 30 years, the most appropriate modality is US because the patient is spared radiation exposure and the likelihood for fibroadenoma is high. Positron emission tomography is expensive and not universally available. Mammography is not indicated as the primary imaging study in women younger than 30 years, unless high-risk factors are present. Computed tomography (CT) scanning is not initially indicated for assessing a palpable lump in a woman in this age group because of radiation exposure, the inability of CT to demonstrate microcalcifications, and the lack of specificity in the findings. Magnetic resonance imaging (MRI) is not initially indicated for assessing a palpable lump in a woman in this age group mainly because of its high cost and the high likelihood of false-positive findings.

On mammograms, fibroadenomas typically appear as circumscribed oval or round masses, which occasionally have coarse calcifications.

On ultrasonograms, fibroadenomas appear as circumscribed, homogeneous, oval, hypoechoic masses that may have gentle lobulations; a smooth, thin, echogenic capsule; variable acoustic enhancement; and homogeneity.

On MRIs, fibroadenomas typically appear as smooth masses with high signal intensity on T2-weighted images and enhancement with the administration of gadolinium-based contrast agent.

Limitations of Techniques

Mammography cannot be used to distinguish whether a mass is a fibroadenoma, a cyst, or a carcinoma with certainty because of some overlap in the findings. All of the entities may appear as smooth masses.

On ultrasonograms, fibroadenomas often demonstrate a typical appearance and may be distinguished clearly from cysts and carcinomas; however, fibrocystic disease with complicated hypoechoic cysts and, rarely, smooth carcinomas may mimic fibroadenoma. Atypical fibroadenomas, which are inhomogeneous or irregular in shape, may simulate carcinomas.

On MRIs, enhancement characteristics may help distinguish fibroadenomas from carcinomas, although the enhancement kinetics and morphologic features of the 2 tumors overlap. Fibroadenomas are hypointense or isointense lesions as compared with adjacent breast tissue on T1-weighted images, and they are hypointense or hyperintense on T2-weighted images. With gadolinium, the majority of fibroadenomas are hyperintense, with slow initial contrast enhancement and a persistent delayed phase, but some have rapid enhancement and either a plateau or a washout phase. Large phyllodes tumors may typically have smooth margins, internal cysts, septations, and hemorrhage or perifocal or unilateral edema, but it is not possible to definitely differentiate between phyllodes tumors and fibroadenomas. Septations occur in about half of fibroadenomas and have been reported to be a strong indicator of this diagnosis, but phyllodes tumors also may have septations. Fibroadenomas may have a contrast-enhancement pattern

suggestiveofmalignancy in up to one third of cases; on MRIs, they cannot be distinguished from phyllodes tumors with certainty.

Definitive diagnosis often requires palpation or image-guided biopsy.

DIFFERENTIALS

Section 3 of 9  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• Mri
• Ultrasound
• Intervention
• Multimedia
• References

Other Problems to be Considered

With mammography or US, circumscribed masses may also represent simple or complex cysts, hamartomas, cystosarcoma phyllodes, lactation adenomas, papillomas, mucinous carcinomas, or medullary carcinomas.

RADIOGRAPH

Section 4 of 9  

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• Introduction
• Differentials
• Radiograph
• Mri
• Ultrasound
• Intervention
• Multimedia
• References

Findings

On mammograms, a fibroadenoma may be occult or may appear as a smooth-margined oval or round mass sized 4-100 mm. Occasionally, tumors contain coarse calcifications, which suggest infarction and involution. Calcifications may be useful in diagnosing the mass, but occasionally, they may mimic malignant microcalcifications. Although fibroadenomas often have coarse calcifications, cystosarcomas rarely have calcifications.

False Positives/Negatives

The mammographic findings of fibroadenomas with hamartomas, cysts, and carcinomas overlap.

MRI

Section 5 of 9  

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• Introduction
• Differentials
• Radiograph
• Mri
• Ultrasound
• Intervention
• Multimedia
• References

Findings

Fibroadenomas appear as round or oval masses that are smooth or gently lobulated and enhance with gadolinium-based contrast material. Internal enhancement in homogeneity may be noted.

Morphology is of utmost importance for correct classification of benign lesions. Fibroadenomas are typically round, ovoid, or lobulated, with smooth margins; however, on early contrast-enhanced images, they may exhibit an irregular shape or margin resulting from the progression of enhancement. Therefore, morphology should be assessed on the noncontrast or late postcontrast images. Nonenhancing internal septa, which are best seen on T2-weighted images, are a specific indicator that a mass is a fibroadenoma; however, they are only seen in a minority of fibroadenomas.

Enhancement kinetics and characteristics are highly variable with fibroadenomas and may be dependent on the degree of fibrosis within the tumor. Enhancement rates of fibroadenomas overlap with those of breast cancers. Mean enhancement is slower in fibroadenomas than in cancers, but this is not useful in assessment of individual cases.

See also Magnetic Resonance Mammography.

Gadolinium-based contrast agents (gadopentetate dimeglumine [Magnevist], gadobenate dimeglumine [MultiHance], gadodiamide [Omniscan], gadoversetamide [OptiMARK], gadoteridol [ProHance]) have recently been linked to the development of nephrogenic systemic fibrosis (NSF) or nephrogenic fibrosing dermopathy (NFD). For more information, see the eMedicine topic Nephrogenic Fibrosing Dermopathy. The disease has occurred in patients with moderate to end-stage renal disease after being given a gadolinium-based contrast agent to enhance MRI or MRA scans.

As of late December 2006, the FDA had received reports of 90 such cases. Worldwide, over 200 cases have been reported, according to the FDA. NSF/NFD is a debilitating and sometimes fatal disease. Characteristics include red or dark patches on the skin; burning, itching, swelling, hardening, and tightening of the skin; yellow spots on the whites of the eyes; joint stiffness with trouble moving or straightening the arms, hands, legs, or feet; pain deep in the hip bones or ribs; and muscle weakness. For more information, see the FDA Public Health Advisory or Medscape.

Degree of Confidence

When internal septa are present in a smooth mass, the confidence that the mass is a fibroadenoma is high. When septa are not present, the findings of fibroadenomas and carcinomas overlap.

ULTRASOUND

Section 6 of 9  

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• Introduction
• Differentials
• Radiograph
• Mri
• Ultrasound
• Intervention
• Multimedia
• References

Findings

Fibroadenomas appear oval on ultrasonograms, and their width is larger than their anteroposterior diameter. Gentle lobulations (typically fewer than 4) may be present, but the margins should be circumscribed.

Internal echogenicity may be homogeneous, and findings may range from isoechoic to lobules of fat to hypoechoic. The through-transmission of the tumor is variable. A thin echogenic capsule is typical of a fibroadenoma and indicates that the lesion is benign. A vague or thick surrounding region of echogenicity may indicate malignancy. Fibroadenomas do not have a true capsule; the thin echogenic capsule seen on ultrasonograms is a pseudocapsule caused by the compression of adjacent tissue.

When using color-flow Doppler or power Doppler imaging, the amount and distribution of vascularity among fibroadenomas is highly variable. Therefore, the vascularity of solid masses does not help distinguish a cancer from a fibroadenoma.

Cysts seen in a solid mass are suggestive of cystosarcoma phyllodes rather than fibroadenomas.

Degree of Confidence

Of masses with a thin, smooth echogenic capsule, 93% are benign. Of circumscribed masses, 91% are benign. Of masses that are round or oval, 94% are benign. Of fibroadenomas, 60% are oriented parallel to the skin (ie, they appear oval).

False Positives/Negatives

Overlap may exist between the US appearances of carcinomas, fibroadenomas, cystosarcoma phyllodes, and complicated cysts.

INTERVENTION

Section 7 of 9  

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• Introduction
• Differentials
• Radiograph
• Mri
• Ultrasound
• Intervention
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Fibroadenoma may be diagnosed by performing stereotactic core breast biopsy (if the mass is visible on mammography) or by performing ultrasound-guided biopsy (if the mass is visible on ultrasonograms). Ultrasound-guided cryotherapy has also been described as a successful, minimally invasive treatment for fibroadenomas.

Cryoablation for breast fibroadenomas has been reported as a safe and effective treatment option to surgical excision.

Medical/Legal Pitfalls

• A repeat biopsy should be performed if histologic findings are not concordant with image-guided biopsy findings. Repeat biopsy can be performed by means of either surgical excision or repeat image-guided biopsy.

MULTIMEDIA

Section 8 of 9  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• Mri
• Ultrasound
• Intervention
• Multimedia
• References

Media file 1:  Ultrasonogram demonstrates a hypoechoic mass with smooth, partially lobulated margins typical of a fibroadenoma.
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Media type:  Image

Media file 2:  Craniocaudal mammograms obtained 1 year apart demonstrate a newly developing mass in the outer part of the breast.
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Media type:  X-RAY

Media file 3:  Spot compression mammogram of the outer part of the breast demonstrates a new mass as smooth, margined, and oval. The findings are consistent with a fibroadenoma, a cyst, or a malignancy. In this patient, the diagnosis was a rapidly growing fibroadenoma.
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Media type:  X-RAY

REFERENCES

Section 9 of 9

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• Mri
• Ultrasound
• Intervention
• Multimedia
• References

• Acha T, Picazo B, Garcia-Martin FJ, et al. Carney''s triad: apropos of a new case. Med Pediatr Oncol. 1994;22(3):216-20. [Medline].
• Alle KM, Moss J, Venegas RJ, et al. Conservative management of fibroadenoma of the breast. Br J Surg. Jul 1996;83(7):992-3. [Medline].
• Courcoutsakis NA, Chow CK, Shawker TH, et al. Syndrome of spotty skin pigmentation, myxomas, endocrine overactivity, and schwannomas (Carney complex): breast imaging findings. Radiology. Oct 1997;205(1):221-7. [Medline].
• Dupont WD, Page DL, Parl FF. Long-term risk of breast cancer in women with fibroadenoma. N Engl J Med. Jul 7 1994;331(1):10-5. [Medline].
• Frayne J, Sterrett GF, Harvey J. Stereotactic 14 gauge core-biopsy of the breast: results from 101 patients. Aust N Z J Surg. Sep 1996;66(9):585-91. [Medline].
• Greenberg R, Skornick Y, Kaplan O. Management of breast fibroadenomas. J Gen Intern Med. Sep 1998;13(9):640-5. [Medline].
• Kaufman CS, Littrup PJ, Freeman-Gibb LA. Office-based cryoablation of breast fibroadenomas with long-term follow-up. Breast J. Sep-Oct 2005;11(5):344-50. [Full Text].
• Kleer CG, Tseng MD, Gutsch DE, et al. Detection of Epstein-Barr virus in rapidly growing fibroadenomas of the breast in immunosuppressed hosts. Mod Pathol. Jul 2002;15(7):759-64. [Medline].
• Kuhl CK. MRI of breast tumors. Eur Radiol. 2000;10(1):46-58. [Medline].
• Littrup PJ, Freeman-Gibb L, Andea A, et al. Cryotherapy for breast fibroadenomas. Radiology. Jan 2005;234(1):63-72. [Medline].
• Markopoulos C, Kouskos E, Mantas D, et al. Fibroadenomas of the breast: is there any association with breast cancer?. Eur J Gynaecol Oncol. 2004;25(4):495-7. [Medline].
• Wurdinger S, Herzog AB, Fischer DR. Differentiation of phyllodes breast tumors from fibroadenomas on MRI. AJR Am J Roentgenol. Nov 2005;185(5):1317-21. [Full Text].

Article Last Updated: Feb 16, 2007