What Is the Proportion of Benign Versus Malignant Breast Masses at Each Age?
To understand the composition and etiology of a breast mass, it is helpful to consider the anatomy of the normal breast. The basic elements include epithelial cells that produce milk (lobules) and ducts that carry milk from the lobules to the nipple during lactation. Connective tissue, fat, and neurovascular elements complete the breast anatomy. There are 4 common etiologies of a breast "lump": fibroadenoma, cyst, other benign fibrocystic masses, and cancer. Figure 1 shows the proportion of each type of breast mass by age.
Etiology of discrete breast lumps. Graph shows prevalence by age of fibroadenoma, cysts, other benign masses, and breast cancer in women. Reprinted with permission from Love N: Primary Care Considerations in Breast Diagnosis, Slide Lecture Program: Slide 40, Copyright © 1992, American Cancer Society, Florida Division Inc.
There is a great deal of confusion about the diagnosis of a fibrocystic mass in the breast. A mass characterized by fibrocystic change is a pathological rather than a clinical diagnosis. A fibrocystic mass is diagnosed based on the presence of 2 important features: fibrous connective tissue and cysts (Fig. 2).
Fibrocystic changes noted on breast biopsy. Note characteristic presence of fibrous connective tissue (white areas) and cysts (rounded opaque areas). Image courtesy of JR Osuch, MD.
When examined microscopically, several varieties of fibrocystic change may be apparent; 2 of these types represent proliferation of the ducts and/or lobules. Referred to as epithelial hyperplasia and atypical epithelial hyperplasia, these are the only variations of fibrocystic change that elevate the risk for breast cancer. Epithelial hyperplasia doubles the relative risk of breast cancer, and atypical epithelial hyperplasia raises the risk of breast cancer 5-fold. The other types of cell changes represent proliferation of breast tissue that do not influence breast cancer risk.
Women often fear the diagnosis of any type of fibrocystic change. While physicians frequently use this diagnosis in their coding mechanisms, it must be made clear to the patient that this is an all-encompassing diagnosis that need not be feared. It is helpful to explain that when this term is used clinically rather than pathologically, reference is literally being made to a noncancerous mass or nodularity.
As seen in Figure 1, fibrocystic changes are very common in premenopausal women, primarily as a result of the influence of ovarian hormones on the physiology of breast tissue. Fibrocystic masses may also appear in some postmenopausal women being treated with HRT. Unfortunately, it is not possible for physical examination or radiological studies to definitively distinguish a fibrocystic from a malignant mass. It is especially dangerous to assign a fibrocystic origin to a change noted on breast examination of a postmenopausal woman; because ovarian function has ceased, postmenopausal women should not be undergoing dynamic breast changes.
A fibroadenoma is a benign mass that occurs most frequently in young women, beginning in adolescence. These masses are usually quite mobile on physical examination and represent a benign proliferation of connective tissue that is encapsulated and incorporates epithelial cells (Fig. 3).
Fibroadenoma removed during breast biopsy. This type of benign mass is usually quite mobile on physical examination and represents benign proliferation of connective tissue that encapsulates epithelial cells. Reprinted with permission from Hughes LE, Mansel RE, Webster DJT: Benign Disorders and Diseases of the Breast: Concepts and Clinician Management (1989; p 63), Copyright © 1989, Bailliere Tindall.
A breast cyst (Fig. 4), like a cyst elsewhere in the body, is a benign, fluid-filled structure. Breast cysts develop through processes of lobular involution and, as such, are found mostly in perimenopausal women. It is uncommon to find cysts in women younger than age 35. Cysts may develop in postmenopausal women, but this is distinctly uncommon unless the woman is taking HRT. Cysts are often firm, which makes them difficult to distinguish, by palpation, from solid abnormalities. Distinguishing the cyst from the solid mass is one of the most important tasks facing the clinician.
Cyst removed during a breast biopsy. Breast cysts, found most commonly in perimenopausal women, are benign, fluid-filled structures that manifest through lobular involution in perimenopausal women. Reprinted with permission from Hughes LE, Mansel RE, Webster DJT: Benign Disorders and Diseases of the Breast: Concepts and Clinician Management (1989; p 93), Copyright © 1989, Bailliere Tindall.
Breast cancer (Fig. 5) does not always present as a mass, but when it does, it is usually firmer than the other breast mass etiologies described. In addition, breast cancer is often painless. However, exceptions to the usual firmness and painlessness of cancerous masses make reliance on such descriptors for diagnosis very hazardous.
Carcinoma removed during breast biopsy. Breast cancer, when presenting as mass, is usually firmer than breast masses of other etiologies. Reprinted with permission from Blamey R, Evans A, Ellis I, et al: Atlas of Breast Cancer (1994; p 35), Copyright © 1994, Merit Publishing International.
Postmenopausal women who present with a breast mass should be presumed to have cancer until it is proven otherwise. (As shown in Figure 1, 85% of breast masses in women 55 years and older are found to be cancerous.) HRT may mitigate the urgency of this caveat, but only to the degree that cysts are more common in postmenopausal women taking estrogen alone or in combination with progesterone. It is noteworthy, however, that each year more than 40,000 women younger than 50 years of age are diagnosed with breast cancer in the US. This makes it necessary for the clinician to pay vigilant attention to any woman who presents with a complaint of a breast mass.
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Cite this: Primary Care Guide to Managing a Breast Mass: Step-by-Step Workup - Medscape - Sep 01, 1999.