MAMMOGRAPHIC FEATURES OF PURE MUCINOUS CARCINOMA OF THE BREAST WITH PATHOLOGICAL CORRELATION

OBJECTIVE: To determine the mammographic features of pure mucinous car cinoma of the breast and correlate them with the pathologic features. PATIENTS AND METHODS: The authors analysed 23 tumours identified as pu re mucinous carcinoma of the breast in 22 patients, aged 40 to 92 (mea n 64.9) years at the time of mammography (which took place between Nov ember 1975 and July 1992). The review covered mammographic features, c linical findings, pathological features and nodal status. RESULTS: Twe nty (87%) of the lesions were palpable, and 4 (17%) were mammographica lly occult. At mammography, eight cases (35%) presented as ill-defined masses without calcifications, five (22%) as well-defined masses with out calcifications, four (17%) as ill-defined masses with calcificatio ns, one (4%) as a focal asymmetric opacity and one (4%) as pleomorphic calcifications only. Eleven (65%) of the 17 mammographically identifi ed masses were irregular in shape, 4 (24%) were oval, and 2 (12%) were lobular. In 11 (61%) of the 18 cases involving masses or an opacity, the lesions were denser than normal breast parenchyma; in the others t he lesions were isodense. All of the hyperdense lesions were greater t han 1.9 cm in greatest diameter, as determined mammographically, where as only one of the isodense lesions was greater than 1.9 cm in greates t diameter. In 17 (77%) of the 22 cases in which the border of the les ions could be evaluated histologically, the lesions had well-defined, pushing borders; the others had ill-defined, irregularly outlined bord ers. Calcifications were seen histologically in seven cases (30%) and were correlated with mammographically suspicious pleomorphic calcifica tions in three. Fourteen (82%) of the 17 patients who underwent axilla ry node dissection were free of nodal disease. CONCLUSIONS: The most c ommon mammographic appearance of pure mucinous carcinoma was an ill-de fined mass and the second most common was a well-defined mass. No spic ulated lesions were observed in this patient group. Microcalcification s were seen in some cases but were less common than in breast cancers in general. Lesions more than 1.9 cm in greatest diameter tended to be hyperdense. A substantial proportion of pure mucinous carcinomas may be mammographically occult.