Classification of breast microcalcifications: radiological-pathological correlation

Microcalcifications play a very important role in detection of breast cancer, especially early stage breast cancer. However, ambiguity still exists in understanding the relationship between radiological and pathological characteristics of microcalcifications. The definitive indication of a biopsy has not been established. The purpose of this study is to evaluate the relationship of classification of breast microcalcifications using full-field digital mammography to the pathological characteristics.

For all the women an open biopsy had been conducted. One hundred and three mammographs showing clustered microcalcifications from 98 consecutive patients were reviewed along with their pathological records. To investigate the value of each criterion for the detection of cancer, univariate and multivariate analyses were performed on the entire sample and then on morphological subgroups.

Pathological examination showed 67 malignant lesions (65.05%) and 36 benign lesions (34.95%). In the univariate analysis, four radiological variables were significant: morphological type (P = 0.001), complicated by a mass (P = 0.002), number of microcalcifications per cluster (P = 0.02) and linear or triangular distribution of clusters (P = 0.009). In the multivariate analysis, two criteria remained significant: morphological type (P < 0.001) and complicated by a mass (P = 0.001). The percentage of malignancy was 37.0%, 60.0%, 78.8%, and 88.9%, respectively, for type 2 (regularly punctiform), type 3 (dusty), type 4 (irregularly punctiform) and type 5 (vermicular) microcalcifications (Le Gal's classification). The malignancy was 78.6% for microcalcifications complicated by a mass and 48.9% without a mass. The difference was significant (P < 0.05). The relationship between morphological types of microcalcifications and the pathological characteristics was also studied. In subgroups, type 3 (dusty) microcalcifications complicated by a mass (P = 0.001) or with the number of microcalcifications more than 10 (P = 0.024); and type 2 (regularly punctiform) with a diameter of the area over 20 mm (P = 0.024) or complicated by a mass (P = 0.025) were statistically significant as criteria for malignant tumour.

Most cases of microcalcifications of type 4 or 5; type 3 complicated by a mass or with the number of microcalcifications more than 10; type 2 complicated by a mass or with a diameter of the area over 20 mm; are indicative of cancer. Open biopsy is recommended to acquire definitive pathological diagnosis for these cases. For the remainder of the morphological types, stereotaxic biopsy or followup should be considered.