Table 1.

Terminology of IPLs.

DIN system	Traditional terminology
Usual ductal hyperplasia (UDH)	Epitheliosis Infiltrating epitheliosis Papillomatosis Sclerosing adenosis with pseudoinfiltration Sclerosing papillary proliferation
DIN1a	Clinging carcinoma monomorphus or type 2 Flat epithelial atypia Atypical cystic lobules Atypical lobules type A Atypical columnar change
DIN1b	Atypical ductal hyperplasia (ADH)
DIN1c	Low-grade ductal carcinoma in situ (LG-DCIS) DCIS grade 1
DIN2	Intermediate-grade ductal carcinoma in situ (IG-DCIS) DCIS grade 2
DIN3	High-grade ductal carcinoma in situ (HG-DCIS) DCIS grade 3