Biopsy must be performed on patients with a dominant or suspicious mass despite absence of mammographic findings (48). Mammography should be performed before biopsy so other suspicious areas can be noted and the contralateral breast can be checked (Fig. 21.2). Mammography is never a substitute for biopsy because it may not reveal clinical cancer, especially when it occurs in the dense breast tissue of young women with fibrocystic changes. The sensitivity of mammography is 75%, with a specificity of 92.3% depending on the patient’s age; breast density; use of hormone therapy; and the size, location, and mammographic appearance of the tumor (49). Mammography is less sensitive in young women with dense breast tissue than in older women, who tend to have fatty breasts, in which mammography can detect at least 90% of malignancies (50). Small tumors, particularly those without calcifications, are more difficult to detect, especially in women with dense breasts.
Ultrasonography Breast ultrasonography is used for focused scanning of a questionable finding or for evaluation of a mammographic finding (51). Reliable, portable, computer-enhanced ultrasonography with high-frequency transducers and improved imaging is available to evaluate and treat problems of the breast (52). It is a sensitive, minimally invasive technique that is used frequently to evaluate some breast symptoms, especially in younger women with dense breast tissue, but is dependent on the availability of a skilled ultrasonographer (53). Some lesions can be detected only with ultrasonography (54). It is the preferred modality to distinguish a solid from a cystic mass (51). Breast ultrasonography is not recommended for routine screening, but is being studied as a means to screen women with dense breast tissue (54). Ultrasonography has a higher false-positive rate than mammography (51,53–55).
Figure 21.2 Bilateral mammography shows the extent of breast carcinoma, illustrating the importance of bilateral mammography in the workup of a clinically apparent mass. (From Kruper L, Giuliano AE. Breast disease. In: Berek JS, Hacker NF, eds. Berek & Hacker’s Gynecologic Oncology, 5th ed. Philadelphia: Lippincott Williams & Wilkins, 2010:617, with permission.)
Following are indications for breast ultrasonography:
Characterization: Palpable abnormality Ambiguous mammographic findings Silicone leak Mass in woman younger than 30 years, lactating, or pregnant
Ultrasonography is useful in distinguishing benign from malignant lesions identified by mammography (56). Ultrasonography may be especially useful if the patient feels a mass, but the physician cannot detect an abnormality and the mammogram does not disclose one. It may identify cancers in the dense breast tissue of premenopausal women, but it is usually used to distinguish a benign cyst from a solid tumor. Ultrasonography cannot reliably detect microcalcifications, and it is not as useful as mammography in assessing women with fatty breasts.
Handheld or real-time ultrasonography is 95% to 100% accurate in differentiating solid masses from cysts (57). This finding is of limited clinical value because a dominant mass should be evaluated by biopsy, and a cystic mass can be studied by needle aspiration, which is far less expensive than ultrasonography. If a lesion proves to be a simple cyst, no further evaluation is necessary. Rarely ultrasonography may identify a small cancer within a cyst, an intracystic carcinoma. These complex cysts warrant surgical biopsy.