Radiographic features of invasive lobular carcinoma of the breast

PURPOSE: To evaluate the radiographic features of invasive lobular carcinoma of the breast. METHODS: We evaluated the radiographic features of 61 cases of histopathologically documented invasive lobular carcinoma. Mammography was performed in all cases. In seven of 61 cases, helical CT with contrast medium was also carried out. Mammographic findings were analyzed to determine true-positive and false-negative rates for the detection of neoplasm. Further, the diameter of the tumor as determined on mammography and helical CT was noted for comparison with the pathologic size. RESULTS: Mammographic features were divided into six types: spiculated mass (38%), indistinct mass (5%), obscured mass (23%), asymmetric opacity (16%), architectural distortion (16%), and no findings (2%). Microcalcifications were present in 12 cases (20%).The overall sensitivity rate was 59%. However, 20 (56%) of 36 cases that were diagnosed as detectable on mammography were underestimated in terms of tumor size compared with the histopathologic findings. Four cases examined by helical CT with contrast medium were compared with the histopathologic findings in terms of extent of the lesion. In three cases, helical CT was more precise than mammography, but the histopathologic findings showed lesions beyond the region evaluated by helical CT. CONCLUSION: Invasive lobular carcinoma is difficult to detect radiographically, and the extent of the lesion tends to be underestimated.