Atypical ductal hyperplasia

“A diagnosis of ADH should not be made unless a diagnosis of low grade DCIS is being seriously considered” WHO Breast 2012

A matter of quantityArchitecture: cribriform spaces, micropapillae

(bulbous), rigid barsCytology: ‘clonal’, monotonous, mild nuclear

atypia, enlarged, nucleoli, distinct cell borders. Same as LG-DCIS

ADH/DCIS

When does ADH become DCIS?A matter of quantity. Criteria still vary and are not standardizedWHO states: > 2 mm and/or completely

involving at least two duct spaces.Any intraductal proliferation with moderate-

high grade nuclear features = DCIS (no size criteria).

Sometimes ADH and UDH co-exist

IHC

IHC : UDH vs ADH/DCIS CK5/6 and ER Caveat: Not helpful in columnar cell change or

apocrine change.

Practical point

If a core biopsy shows borderline features of ADH/DCIS, be conservative and call it ‘at least ADH’

An upgrade rate to DCIS on excision is well known and accepted.

Harder to explain DCIS, limited to the core.

ER

CK5/6