In your everyday breast practice, most carcinomas will present either with a mass lesion or microcalcifications. The third manner of presentation is parenchymal asymmetry or distortion. Sometimes the distortion is there without a mass. In reality, this usually poses the biggest challenge to early diagnosis.
All is not lost. You can train your eyes to become used to what the distortions look like if you see enough of them. Here is another very subtle example of a distortion that turned out to be an IDC with node metastases.
Look at the annotated image and try and find these "runners" on the mammograms you read even if there is no asymmetrical density seen. The runners can be an early clue and ultrasound is your friend.