Teaching Case

No history of breast cancer – Routine mammography

Married - 2 children <> Last period 10 years ago <> No family history of breast cancer <> No personal history of breast cancer <> No hormone replacement therapy <> Right breast surgical biopsy 5 years ago – benign <> 1988 mammography for right breast pain <> 1989 mammography for suspected right breast mass <> 1991 routine mammography

Breasts are fairly symmetric organs. They might differ in size but their inner structures are mostly symmetric. The observer is often in the situation of deciding if a given asymmetry within a examination is due to a difference in positioning or it is a real finding. To be significant, asymmetry should be three dimensional, should be viewed in both projections and should be stable even on spot compression films. ASYMMETRIC BREAST TISSUE is a normal variant. It has not a center, it is stable over time, there is no architectural distortion accompanying it and can not be detected by clinical examination. It may be found in about 3% of the investigated population, mostly in the upper outer quadrant of the breast. Ultrasound examination of this finding has not been shown to add any clinically useful information, as long as there is no reason to suspect a mass in the region.[1] NEODENSITY on the other hand, even without well defined margins or center, even when not seen in both projections, but which is stable on spot compression films, should be viewed with suspicion and further investigated. DEVELOPING DENSITY should be regarded as an abnormal process since breast is an involuting organ, process which starting for most women in their 30s. Breast density may grow, sometimes unhomogeneously during hormone replacement therapy or in cases when the patient looses a significant amount of weight and therefore a significant amount of fat from her breasts. It have to be pointed out that Invasive Lobular Carcinoma is acknowledged as a cause for unhomogeneous densities interspersed with breast tissue, without microcalcifications and only in late stages accompanied by architectural distortion. FOCAL ASYMMETRIC DENSITY if not proved to be an island of benign breast tissue, is an abnormal process, mostly due to a mass with ill defined margins, a denser center, seen in both projections and stable on spot compression views.[2] It might represent almost 14% of the probably benign lesions discovered at screening but only 0.4% of them prove to be cancers.[3] From what was said up to this point, it is clear that besides spot compression films, one of the most important methods at our disposal in clarifying the nature of a density or any other mammographic finding, is the COMPARISON WITH PREVIOUS MAMMOGRAMS. Using previous mammograms in the diagnostic process may be rewarding in two ways. One of them is that as it had been shown, fewer incorrectly abnormal screening interpretations are made when previous examination films are available for comparison. The other benefit from comparing mammograms with previous examinations is that the yield of the biopsies performed on lesions found by second mammogram, grows by 10% when comparison is made with the previous study. The lesions removed are smaller and they are in an earlier stage. There is an impression that the percentage of negative lymph nodes is higher for the lesions discovered at the second screening.[4] Comparison with previous films should be performed whenever they are available and it should be performed with ALL previous films, not only with the last examination. N.B. – The case brought to illustrate the problem of asymmetric and developing density, is also a case of misinterpretation of the mammographic reports. In spite of the fact that the findings within the right breast were reported as suspicious, based on clinical findings only, the surgeons decided to clinically follow-up the patient. Only 14 month following the last mammogram the patient had a surgical biopsy followed by completion mastectomy and lymph node dissection.