Fibroadenoma
Classification and external resources
Histopathologic image of breast fibroadenoma. Core needle biopsy. Hematoxylin & eosin stain.
ICD-10	D24
ICD-9	217
ICD-O:	M9010/0-M9012, M9020, M9030
DiseasesDB	1595
MedlinePlus	007216
eMedicine	radio/109
MeSH	D018226

Fibroadenomas of the breast, are lumps composed of fibrous and glandular tissue. Because breast cancer can also appear as a lump, doctors may recommend a tissue sample (biopsy) to rule out cancer in older patients. Unlike typical lumps from breast cancer, fibroadenomas are easy to move, with clearly defined edges.^[1][2]

Fibroadenomas are sometimes called breast mice or a breast mouse owing to their high mobility in the breast.^[3]

  Signs and symptoms

The typical case is the presence of a painless, firm, solitary, mobile, slowly growing lump in the breast of a woman of childbearing years.^[2][4][5]

In the male breast, fibroepithelial tumors are very rare, and are mostly phyllodes tumors. Exceptionally rare case reports exist of fibroadenomas in the male breast, however these cases may be associated with antiandrogen treatment.^[6]

  Diagnosis

  Fibroadenoma in ultrasound

A fibroadenoma is usually diagnosed through clinical examination, ultrasound or mammography, and often a needle biopsy sample of the lump.^[4]

  Etiology and epidemiology

Fibroadenomas arise in the terminal duct lobular unit of the breast.^{[citation needed]} They are the most common breast tumor in adolescent women. They also occur in a small number of post-menopausal women. Their incidence declines with increasing age, and, in general, they appear before the age of thirty years. Fibroadenomas are partially hormone-dependent and frequently regress after menopause. They are hypovascular compared to typical (especially malignant) neoplasms.^[2][7][5]

Higher intake of fruits and vegetables, higher number of live births, use of oral contraceptives and moderate exercise are associated with lower frequency of fibroadenomas. ^[8]

  Pathology

  Macroscopic view of fibroadenoma of the breast

  Cytology

The diagnostic findings on needle biopsy consist of abundant stromal cells, which appear as bare bipolar nuclei, throughout the aspirate; sheets of fairly uniform-size epithelial cells that are typically arranged in either an antler-like pattern or a honeycomb pattern. These epithelial sheets tend to show typical metachromatic blue staining on DiffQuick staining. Foam cells and apocrine cells may also be seen, although these are less diagnostic features.^[4][7] The gallery images below demonstrate these features.

  Macroscopic

Approximately ninety percent of fibroadenomas are less than three centimetres in diameter. The vast majority of the remaining ten percent that are four centimetres or larger occur mostly in women under twenty years of age. The tumor is round or ovoid, elastic, and nodular, and has a smooth surface. The cut surface usually appears homogenous and firm, and is grey-white or tan in colour. The pericanalicular type (hard) has a whorly appearance with a complete capsule, while the intracanalicular type (soft) has an incomplete capsule.^[7]

  Microscopic

Fibroadenoma of the breast is a benign tumor composed of two elements : epithelium and stroma. It is nodular and encapsulated, included in breast. The epithelial proliferation appears in a single terminal ductal unit and describes duct-like spaces surrounded by a fibroblastic stroma. Depending on the proportion and the relationship between these two components, there are two main histological features : intracanalicular and pericanalicular. Often, both types are found in the same tumor. A) Intracanalicular fibroadenoma : stromal proliferation predominates and compresses the ducts, which are irregular, reduced to slits. B) Pericanalicular fibroadenoma : fibrous stroma proliferates around the ductal spaces, so that they remain round or oval, on cross section. The basement membrane is intact ^[9] The gallery image below demonstrates both morphological subtypes.

  Treatment

Most fibroadenomas are left in situ and monitored by a doctor, or the patient in question. Some are treated by surgical excision. They are removed with a small margin of normal breast tissue if the preoperative clinical investigations are suggestive of the diagnosis. A small amount of normal tissue must be removed in case the lesion turns out to be a phyllodes tumour on microscopic examination.^[7][10]

Because needle biopsy is often a reliable diagnostic investigation, some doctors may decide not to operate to remove the lesion, and instead opt for clinical follow-up to serially observe the lesion over time using clinical examination and mammography to determine the rate of growth, if any, of the lesion. A growth rate of less than sixteen percent per month in women under fifty years of age, and a growth rate of less than thirteen percent per month in women over fifty years of age have been published as safe growth rates for continued non-operative treatment and clinical observation.^[11]

Some fibroadenomas respond to treatment with ormeloxifene.^[12]

Fibroadenomas have not been shown to recur following complete excision or transform into phyllodes tumours following partial or incomplete excision.^[7]

There are also natural treatments being touted to diminish fibroadenomas, such as Fibrosolve, but no definite studies have been made as to prove their effectiveness.

  Cryoablation Treatment

The FDA has approved cryoablation (the use of extreme cold to destroy tissue) of a fibroadenoma as a safe, effective and minimally-invasive alternative to open surgical removal.^[13] In the procedure, ultrasound imaging is used to guide a probe into the mass of breast tissue. Extremely cold temperatures are then used to destroy the abnormal cells,^[14] and over time the cells are reabsorbed into the body. The procedure can be performed in an office setting with local anesthesia only, and leaves substantially less scarring than open surgical procedures.^[14]

The American Society of Breast Surgeons recommends the following criteria to establish a patient as a candidate for cryoablation of a fibroadenoma:^[13]

1. The lesion must be sonographically visible.
2. The diagnosis of fibroadenoma must be confirmed histologically.
3. Lesions should be less than 4 cm in diameter.

  Fibroadenoma images

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  Fibroadenoma Histology (H&E). The image demonstrates intracanalicular morphology (top right) and pericanalicular morphology (bottom left)

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  Fibroadenoma, Fine Needle Aspiration Biopsy (Giemsa or DiffQuick^TM stain). The image shows abundant bare bipolar stromal nuclei surrounding sheets of metachromatic epithelial cells.

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  Fibroadenoma, Fine Needle Aspiration Biopsy (Papanicolou stain). The image shows a sheet of epithelial cells in the typical antler pattern.

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  Histopathologic image of breast fibroadenoma. Core needle biopsy. Hematoxylin & eosin stain.

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  Video on Fibroadenoma

• Fibroadenoma Video
• The Doctors Show: Fibroadenoma Cryoabltaion on YouTube

  References