Fibroadenomas are the most common tumor of youth and early adulthood.
With increasing age, they may hyalinize or calcify. Fibroadenomas
are composed of the normal tissues of the breast just in an abnormal
formation; thus, they can have carcinoma within them. But the
risk of cancer within a fibro adenoma is no greater than that
of other breast tissue.
Fibroadenomas are estrogen stimulated and are frequently identified
in women of reproductive age, usually between the ages of 15 and
35 years, with a mean age of 30 years. Because they are hormonally
stimulated, they can grow rapidly in pregnant women. Rarely are
new fibroadenomas found in postmenopausal women with or without
HRT. These masses, as with any new solid mass in a postmenopausal
woman, should be considered highly suspicious for cancer, and
tissue diagnosis is essential.
Juvenile fibroadenomas are found in adolescents and can have extremely
rapid growth, to the point of deforming the breast and causing
nipple displacement. They may be multiple and bilateral. Sonographically,
they are indistinct from other fibroadenomas. When large, these
masses can concurrently be called juvenile and giant.
Sonographic Findings :
Fibroadenomas are smooth or macrolobulated masses that are more
wide than tall. Usually they measure less than 3 cm. These lesions
displace rather than infiltrate surrounding tissue, making them
well-marginated masses. They are typically homogeneous with low-level
internal echoes but can show areas of cystic necrosis if they
outgrow their blood supply. Posterior acoustic enhancement is
present in a large percentage of fibroadenomas, although any acoustic
transmission pattern may be present in uncalcified fibroadenomas,
including posterior acoustic shadowing.. "Popcorn" calcifications
can form, and sonographically these masses may completely attenuate
the ultrasound beam, producing significant posterior shadowing.
An ultrasound examination may not be of assistance in these cases.
Peripheral vascularity may be visualized with Doppler.