Exercise: Architectural Distortion and Asymmetric Density(The Asymptomatic Patient)

EXERCISE 5-4. ARCHITECTURAL DISTORTION AND ASYMMETRIC DENSITY

5-12. Concerning the architectural distortion in the right breast in Case 5-12 (Figure 5-22), which statement is false?

A.         Without history of biopsy, scarring is unlikely.

B.         Previous mammograms could be very helpful.

5-13.    The mammographic appearance in Case 5-13 (Figure5-23) is least likely to be caused by normal breasts,postsurgical change.,trauma, cystic disease,tumor.

Radiologic Findings

5-12.Bilateral craniocaudal views show architecture dis-tortion in the right breast without a discrete domi-nant mass (C is the correct answer to Question 5-12).

5-13.Bilateral mediolateral oblique views of patient in thiscase show areas of asymmetric density in the left upper and right lower breast. The densities are inter-spersed with fat. Margins are generally concave, and there is no architectural distortion (D is the correct answer to Question 5-13).

Discussion

Although normal breast tissue is remarkably symmetric, it is never exactly the same on both sides. The challenge in mam-mography is to recognize normal variation and to be able to distinguish nonpathologic asymmetry from disease. This is not always possible, particularly in the asymptomatic group. A high index of suspicion is needed in evaluating the screen-ing mammogram, just as in the baseline clinical breast exam-ination. Once asymmetry is noted mammographically, a careful, focused breast examination is needed. If no suspi-cious areas are detected and if the radiographic features sug-gest fibroglandular tissue, then follow-up alone is adequate. Radiographically, we look for a homogeneous, nondistorted pattern of fat interspersed with lobular densities. Any domi-nant mass or architectural distortion should cause concern.

In Case 5-12, one area shows a different architectural pat-tern. The lines of tension appear to pull to a central focus. This is a classic appearance of invasive lobular carcinoma. Remember that 90% of the breast cancers are ductal in ori-gin, and the other 10% are lobular, as in this case. This type of carcinoma shows a subtle infiltrating pattern much more often than does ductal carcinoma (Statement D is true).

One of the problems with this disease is that it is difficult to describe the extent of tumor mammographically. There is a large area of asymmetric architecture in this patient, but where the tumor ends is unclear. This patient had a carci-noma that measured 4 cm.

A correlated clinical examination often reveals abnormal-ities not detected without the guidance of mammographic findings (Statement C is false). Biopsy of any suspicious-feeling area is strongly recommended. Studies have shown that a high percentage of carcinomas “missed” at mammog-raphy appear as architecture distortion or asymmetric den-sity. This patient did have a large area of thickening in the upper aspect of this breast, confirming the suspicious nature of the mammographic findings.

Previous mammograms are definitely useful in evaluating architecture distortion and asymmetric density. If the finding is unchanged over time, no further action may be needed. If the finding is new or is increasing, it is more easy to recognize (Statement B is true). Hormonal therapy may indeed have an asymmetric effect (Statement E is true), but it does not take the form of architecture distortion.

Surgical biopsy may result in such distortion of the archi-tecture, but precise correlation with location and timing of the surgery is needed (Statement A is true).

Unlike the previous patient, the woman in Case 5-13 has multiple areas of breast asymmetric density. There is a large area in the upper part of the left breast and a smaller area in the lower part of the right breast. Both areas show fat inter-spersed with fibroglandular densities. There is no architec-tural distortion. Margins of the larger opacities are generally concave—a sign of benignity. There are no dominant or cir-cumscribed masses, and cystic disease therefore would not be part of the differential diagnosis, because cysts are rounded masses. Having learned from the previous case that missed carcinoma often presents as asymmetric density, tumor must remain in the differential diagnosis, and answer E is incorrect.

Both trauma and postoperative change can lead to ill-defined asymmetric density. With trauma there may be bleeding, contusion, or actual deformity, if severe. With sur-gery, asymmetry results both from removal of normal tis-sues, leaving less density on the operated side, and from surgical trauma (hematoma and distortion), which causes increased localized densities. Therefore, options B and C are both incorrect. The most likely cause of this woman’s mam-mographic appearance is normal breast tissue, and answer A is incorrect. The multiplicity and bilaterality of areas of asymmetry, the lack of signs or symptoms of breast cancer, and the fibroglandular characteristics of the densities all support this diagnosis.