[223] Detailed Characterization of Ductal Carcinoma In Situ Associated with a Mass on Imaging

Aparna Mahajan, Luis Z Blanco, Jr., Lilian C Wang, Ellen B Mendelson, Kalliopi P Siziopikou, Megan E Sullivan. Northwestern University, Chicago, IL

Background: With mammographic screening, it is uncommon for ductal carcinoma in situ (DCIS) to present as a mass. When a core biopsy (CB) targeting a mass yields only DCIS, pathologic-radiologic concordance can be challenging. We reviewed DCIS diagnosed by CB targeting a mass to determine how often a pathologic mass is present. Myoepithelial markers (MEM) can be reduced or negative in some mass forming DCIS-like lesions such as encapsulated papillary carcinoma (EPC). MEM were evaluated to see if any specific histologic features were associated with reduced expression.
Design: The EMR was searched from 2007-10 for CB targeting a mass with a diagnosis of DCIS. CB with ipsilateral invasive carcinoma (IC) or DCIS involving a benign mass (e.g. fibroadenoma) were excluded. All slides were reviewed and pertinent data including grade, type and stromal charateristics were recorded. CB were categorized as 1) mass forming with normal ductal architecture; 2) mass forming with distorted architecture (back-to-back or irregular); or 3) no clear mass. At least 2 MEM (p63, SMMHC, calponin and CD10) were performed on all CB. When the intensity of MEM around DCIS was less than in benign ducts, it was considered reduced. Results of the subsequent excision were recorded when available.
Results: 55 CB met inclusion criteria; 45% were BIRADS 4C/5. 93% (51/55) had high grade DCIS. 73% (40/55) had a pathologic mass on CB and of these 60% had architectural distortion. 33% of CB with distortion had papillary type DCIS vs. 6% (1/16) of CB with normal architecture. No clear pathologic mass was identified in 15 cases. 53 of the 55 cases had available excisions (Table 1). MEM were adequate on 50 CB and positive in 49, with reduced expression in 34. 53% with reduced MEM were upgraded vs. 27% with strong MEM.

Table 1: Results
 Papillary FeaturesIC on Excision
Pathologic Mass (N=40)9 (23%)16 (40%)
No Mass (N=15)0 (0%)9 (64%)
Positive MEM (N=15)3 (20%)4 (27%)
Reduced MEM (N=34)5 (15%)18 (53%)
Negative MEM (N=1)1 (100%)0

Conclusions: CB of mass forming DCIS often show architectural distortion (60%) and have a papillary component (23%). CB with no pathologic mass had the highest upgrade rate (64%) suggestive of undersampling. Reduced expression of MEM was seen more often in CB with papillary features and may indicate a possible EPC component. CB with reduced MEM also had a higher upgrade rate. Complete negativity with multiple MEM in lesions that otherwise look like DCIS is a rare but problematic occurrence on CB and requires further study.
Category: Breast

Monday, March 4, 2013 1:00 PM

Poster Session II # 52, Monday Afternoon


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