Clinical history: This 58 year-old woman with history of previous breast biopsy consistent with papillary lesion, likely intraductal papilloma with atypical features. She underwent vacuum assisted biopsy for a larger sample and definitive diagnosis.
What is your diagnosis?
Discussion and answer
Diagnosis: Papillary carcinoma
Sections reveal a papillary proliferation with some areas showing thick vascular cores, in places these cores are sclerosing. Other areas however show at least atypical proliferation either micropapillary or with somewhat stiff architectural arrangements (similar to that seen in DCIS). The interface with what looks like a thin fibrous capsule between lesion and breast tissue is pushing and not infiltrative in nature. Adjacent to the papillary lesion there is DCIS (cribriform, low grade). IHC for P63 and CD10 were done and the areas of DCIS are nicely surrounded by a myoepithelial layer (not shown) and is negative within the papillary lesion.
The interface between the papillary lesion and surrounding fibrous
capsule is negative. This negative staining can be consistent with either an "encapsulated" invasive papillary carcinoma or a frankly invasive carcinoma (some authors actually consider all these lesions as invasive although with a good prognosis). In summary the features are those of a papillary carcinoma with the features in this sample of a circumscribed, so called encapsulated/ non-invasive papillary carcinoma with adjacent DCIS. The lesion requires complete excision to assess further with respect to the degree to which a more frankly invasive carcinoma is present.