Final answer:
Lobular carcinoma is the type of breast cancer that is notoriously difficult to detect on mammography and often requires an ultrasound for better visualization, followed by a biopsy for a definitive diagnosis.
Step-by-step explanation:
The type of breast cancer that is difficult to detect on mammography is Lobular carcinoma; it is often better visualized using ultrasound. The tissue composition in lobular carcinoma does not differ significantly from the surrounding tissue on a mammogram, making it less noticeable. Unlike ductal carcinoma in situ (DCIS), which typically presents with calcifications that are detectable on a mammogram, lobular carcinoma does not always produce these changes, thus requiring different imaging techniques for detection. A biopsy is a crucial step for diagnosing breast cancer to determine the exact nature and stage of the cancer.