Can we manage B3 lesions better?

Within mammographic breast screening programmes in Europe, a categorisation for nonoperative histology reporting is used from B1 normal and B2 benign through to B5 malignant. Definitive diagnosis is possible for the majority of lesions on core biopsies, but there remains a small proportion in the borderline category of B3, uncertain malignant potential. These are lesions that are either benign but known to be associated with malignancy, or which are known to be heterogeneous and where sampling may have missed a more worrisome area.

B3 lesions include entities such as radial scars, papillary lesions and phyllodes tumours. Often more diagnostically difficult for the pathologist are the atypical epithelial proliferations such as atypical intraductal proliferations (akin to atypical ductal hyperplasia), lobular neoplasia and columnar cell atypia/flat epithelial atypia.

Advances have been made regarding management of some of these processes; it is established that the atypical intraductal epithelial proliferations are more frequently definitively upgraded with the use of wider gauge devices (for example, 11 G, 8 G) to ductal carcinoma in situ. In such cases, diagnostic excision can be avoided and therapeutic surgery undertaken. Conversely, it has been shown that some papillary lesions may be excised by mammotomy.

There are still few robust data, however, on outcome following a B3 diagnosis of lobular neoplasia or of flat epithelial atypia. The management of these lesions when identified in the core can cause controversy and debate. Collaborative data collection of the outcome of these uncommon entities is central to resolving the question of optimal clinical management.