A 45-year-old woman undergoes core biopsy of a breast mass. Pathology shows large pleomorphic cells filling and distending ducts with central comedonecrosis and calcifications. Grade 3 DCIS is present. The comedonecrosis pattern of DCIS is most specifically associated with which molecular subtype of breast cancer?

• A Luminal A (ER+/PR+, HER2-, low Ki-67)
• B Normal breast-like subtype
• C Lobular carcinoma in situ (LCIS) with E-cadherin loss
• D HER2-enriched or triple-negative (basal-like) subtype with high proliferation index ✓

Explanation

High-grade (Grade 3) DCIS with comedo-type necrosis is associated with HER2-enriched or triple-negative molecular subtypes with high Ki-67 proliferative index, aneuploidy, and nuclear pleomorphism. These subtypes carry a higher risk of progression to invasive carcinoma. Luminal A DCIS is typically low grade, non-comedo pattern. LCIS is characterised by E-cadherin loss and dyscohesive cells.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.