Table II.

Essential and Desirable Diagnostic Criteria for IDC-P.

Essential criteria	Expansile epithelial proliferation in the pre-existing duct-acinar system
	Lumen-spanning solid, dense cribriform, and/or comedo patterns
	Loose cribriform or micropapillary patterns with enlarged pleomorphic nuclei*
	Residual basal cells
Desirable criterion	Immunohistochemistry demonstrating at least partial basal cell retention

*The specific size criterion (6x size of adjacent benign nuclei) has been removed in the current edition of WHO Blue Book.