Table 1. Morphological and IHC Features of IDC-P and HGPIN.

Histological features	IDC-P	HGPIN
Growth patterns	Usually solid and/or dense cribriform, and less often flat, loose cribriform, micropapillary, tufted	Micropapillary, tufted, loose cribriform and flat
Size and contour of glands	Enlarged glands with irregular outlines and branching contours	Glands similar in size to adjacent benign glands with relatively smooth rounded contours
Number of glands	≥6 contiguous glands	Usually less than 6 contiguous glands
Nuclear size	≥6 times normal nuclear size	2–3 times normal nuclear size
Nuclear pleomorphism	Marked high-grade features	Low-grade features
Mitotic activity	Prominent	Rare
Comedonecrosis	Non-focal comedonecrosis	Very rare, focal (if present)
ERG IHC	Positive in significant number of cases, both with and without invasive carcinoma	Rarely positive
PTEN IHC	Frequent loss	No loss

IDC-P, intraductal carcinoma of prostate; HGPIN, high grade prostatic intraepithelial neoplasm; IHC, immunohistochemistry.