A Proposal to Define Three New Breast Calcification Shapes: Square, Sandwich, and Teardrop, Pill & Capsule

To define and illustrate three new descriptors for microcalcification morphology on mammography, and provide a preliminary assessment of their potential clinical value.

The institutional review board approved this retrospective study and waived the requirement for informed consent. One thousand consecutive biopsy-proven cases of microcalcifications were retrospectively reviewed by the index study observer, a fellowship-trained breast radiologist blinded to histologic outcome. Each case was evaluated for traditional Breast Imaging Reporting and Data System (BI-RADS) morphology descriptors, as well as for the presence of one of three proposed new calcification morphology descriptors: (1) square, (2) sandwich, and (3) teardrop, pill & capsule. Positive predictive value (PPV) for each proposed shape was calculated. Interobserver variability was calculated on a subset of 200 cases, which were evaluated by two additional breast radiologists blinded to the interpretation of the index observer.

Of 1000 cases, 702 (70.2%) were benign, and 298 (29.8%) were malignant. There were 51 (5.1%) square and 60 (6.0%) sandwich calcification cases, which were all benign at biopsy (PPV, 0%). Of the 106 (10.6%) cases that included teardrop, pill & capsule calcifications, 90 were malignant (PPV, 84.9%). Interobserver variability for the traditional BI-RADS morphology descriptors (κ = 0.40) was comparable to observer variability of the proposed new morphologies: square (κ = 0.39), sandwich (κ = 0.47), and teardrop, pill & capsule (κ = 0.49).

The proposed calcification descriptors square and sandwich-shaped had a PPV of 0%, and they may represent new typically benign morphologies. In contrast, teardrop, pill & capsule-shaped calcifications indicate a higher likelihood of malignancy than that of previously established descriptors.