Breast tumour. Ultrasound scan of a patient with a fibroadenoma (indicated at upper centre) in her breast. Fibroadenomas are tumours that are composed of both fibrous and glandular tissue. They are usually benign. Fibroadenomas are usually left untreated, as they can disappear over time, but if the tumour is large or painful then it may be surgically removed. Ultrasound is a diagnostic technique that sends high frequency sound waves into the body via a transducer. The returning echoes are recorded and used to build an image of an internal structure.