Fibroadenoma
This is the most common benign tumor of the female breast. Occurring at any age within the reproductive period of life, fibroadenomas are somewhat more common before age 30. They are frequently multiple and bilateral. Young women usually present with a palpable mass and older women with a mammographic density ( Fig. 23-28A ) or mammographic calcifications. The epithelium of the fibroadenoma is hormonally responsive, and a slight increase in size may occur during the late phase of each menstrual cycle. An increase in size due to lactational changes or, not uncommonly, infarction and inflammation may lead to a fibroadenoma mimicking carcinoma during pregnancy. Regression usually occurs after menopause. The stroma often becomes densely hyalinized and may calcify. Large lobulated ("popcorn") calcifications have a characteristic mammographic appearance, but small calcifications may appear clustered and require biopsy to exclude carcinoma.
Morphology.
Fibroadenomas grow as spherical nodules that are usually sharply circumscribed and freely movable in the surrounding breast substance. They vary in size from less than 1 cm in diameter to large tumors that can replace most of the breast. Grossly, the tumors are well-circumscribed, rubbery,
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grayish white nodules that bulge above the surrounding tissue and often contain slitlike spaces ( Fig. 23-28B ).
The stroma is usually delicate, cellular, and often myxoid, resembling intralobular stroma, enclosing glandular and cystic spaces lined by epithelium. The epithelium may be surrounded by stroma or compressed and distorted by it ( Fig. 23-29 ). In older women, the stroma typically becomes densely hyalinized and the epithelium atrophic.
Some fibroadenomas are polyclonal in origin and are probably due to focal hyperplasia of lobular stroma. For example, almost half of women receiving cyclosporin A after renal transplantation develop fibroadenomas.[82] The tumors are frequently multiple and bilateral and are likely to be due to drug-related growth stimulation. On the other hand, there is a subset of fibroadenomas that are benign neoplasms of stromal cells. Multiple studies have shown that in some tumors, the fibrous (stromal) component is clonal and may have cytogenetic aberrations, but the epithelial component is polyclonal. No consistent cytogenetic changes have been found.[83] [84]
Fibroadenomas were originally grouped with other "proliferative changes without atypia" in conferring a mild increase in the risk of subsequent cancer. However, in one study, only fibroadenomas associated with cysts larger than 0.3 cm, sclerosing adenosis, epithelial calcifications, or papillary apocrine change ("complex fibroadenomas") conferred a mild increase in the risk of subsequent breast cancer[85] ( Table 23-2 ). It is hoped that future studies will better define the risk associated with these lesions.
תמונות שמצוטטות בטקסט:
Figure 23-28 A, This mammogram shows a well-circumscribed mass. (Courtesy of Dr. Jack Meyer, Brigham and Women's Hospital, Boston, MA.) Although the most common lesion would be a fibroadenoma, other benign (e.g., fibrous lesions or PASH) and malignant (e.g., medullary or mucinous carcinomas) lesions can also have this appearance. B, Fibroadenoma. A rubbery, white, well-circumscribed mass is clearly demarcated from the surrounding yellow adipose tissue. The fibroadenoma does not contain adipose tissue and therefore appears denser than the surrounding normal tissue on mammogram.
Figure 23-29 Fibroadenoma. The lesion consists of a proliferation of intralobular stroma surrounding and often pushing and distorting the associated epithelium. The border is sharply delimited from the surrounding tissue.
מצוטט בפיסקה האחרונה של הטקסט (נראה לי לא רלוונטי לחלוטין):
Pathologic Lesion / Relative Risk of Developing Invasive Carcinoma / Breast at Risk / Modifiers of Risk /
Nonproliferative Breast Changes / 1.0 / Neither
Duct ectasia
Cysts
Apocrine change
Mild hyperplasia
Adenosis
Fibroadenoma without complex features
Proliferative Disease Without Atypia / 1.5–2.0 / Both breasts / Increased risk if there is a family history of breast carcinoma
Moderate or florid hyperplasia / Decreased risk 10 years after biopsy
Sclerosing adenosis
Papilloma
Complex sclerosing lesion (radial scar)
Fibroadenoma with complex features
Proliferative Disease with Atypia / 4.0–5.0 / Both breasts / Increased risk if there is a family history of breast carcinoma
Atypical ductal hyperplasia / Increased risk if premenopausal
Atypical lobular hyperplasia / Decreased risk 10 years after biopsy for ALH
Carcinoma in Situ / 8.0–10.0
Lobular carcinoma in situ / Both breasts / Treatment (tamoxifen, bilateral mastectomy)
Ductal carcinoma in situ * / Ipsilateral breast / Treatment (tamoxifen, surgery to eradicate the lesion, radiation therapy)
*This risk applies to low-grade DCIS originally misdiagnosed as benign disease and followed without treatment. The risk for progression of high-grade DCIS is presumed to be greater than this.