A core needle biopsy from a 45-year-old woman with a mammographic density shows a proliferation of monomorphic cells arranged in rigid secondary spaces, measuring less than 2 mm in extent, with low-grade nuclei. Which of the following best describes this finding?

• A Usual ductal hyperplasia
• B Ductal carcinoma in situ (low grade)
• C Atypical ductal hyperplasia ✓
• D Lobular carcinoma in situ

Explanation

Atypical ductal hyperplasia (ADH) shows partial duct filling by monomorphic cells with low-grade nuclei, rigid secondary spaces, and measures less than 2 mm. It is a borderline lesion with increased relative risk (approximately 4 to 5 fold) of subsequent breast cancer. Low-grade DCIS would show complete duct filling by the same cells. Usual ductal hyperplasia shows heterogeneous cells without rigid architecture. LCIS involves lobules, not ducts.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.