Papillary Breast Lesions: An Overview



General

  • Characterized by epithelial proliferation supported by fibrovascular cores +/- intervening myoepithelial cell layer

  • Carcinomas with predominantly papillary morphology have a better outcome




COMMON BENIGN FEATURES

  • Papillary lesion has a double cell layer (myoepithelial cells stain with p63 or calponin and are present in papillary fronds & periphery of involved space)

  • Epithelial cells have NO atypia- (NOTE: you can see ADH or DCIS in an IDP; Restricted luminal (pink) cytokeratin expression without brown myoepithelial cells supports the diagnosis of ADH)

  • Thick collagenous stroma within branching fibrovascular cores. Can have marked fibrosis (“sclerosing papilloma”). The overall appearance is heterogeneous with thick fibrovascular cores and other areas of adenosis.

  • Finding apocrine metaplasia is helpful (common in benign papillomas; unusual in papillary carcinomas)


ATYPICAL/MALIGNANT FEATURES

  • Increased cellularity surrounding the fibrovascular cores

  • Numerous epithelial cells not directly connected to a papilla (thin papillations)

  • Lack of myoepithelial cells

  • Fibrovascular cores can be very small and subtle (benign FV cores are thicker/more fibrotic)

  • Mitotic figures

  • Architectural complexity (Low power view may demonstrate circumscription and this within a dilated duct)





Papillary Breast Lesions: Common Diagnoses


Benign lesions:

  • Solitary (central) papilloma

  • Multiple (peripheral) intraductal papillomas

  • Atypical lesions:

  • Intraductal papilloma with ADH or DCIS

Malignant lesions:

  • Papillary DCIS

  • Encapsulated papillary carcinoma

  • Solid papillary carcinoma

  • Invasive papillary carcinoma


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