Atypical ductal hyperplasia is a histologically borderline lesion that has some, but not all, of the features of ductal carcinoma in situ. Sometimes the distinction between Atypical ductal hyperplasia and ductal carcinoma in situ are simply defined on the number of ducts involved.
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Pathology
Atypical ductal hyperplasia is a lesion with malignant potential. It lacks the strict criteria for ductal carcinoma in situ, with <2 ducts involved 3.
Radiographic features
Mammography
Grouped or regional amorphous calcifications. Less likely are punctate or fine pleomorphic calcifications 6.
Ultrasound
Solid or intracystic mass.
MRI
Non-specific features on MRI range from a round, oval or irregular mass to non-mass enhancement in a focal, linear, segmental or regional distribution 6.
Treatment and prognosis
Atypical ductal hyperplasia is considered a high-risk breast lesion. Therefore surgical excision is advised as under-estimation of ductal carcinoma in situ is encountered when atypical ductal hyperplasia is retrieved on a large core needle biopsy (up to one-third of cases may be upstaged to ductal carcinoma in situ). Tamoxifen may be used as a chemopreventative agent.