[189] Extravasated Mucin Pools in Breast Core Needle Biopsy: Ten Year Experience at a Single Institution

M Edelweiss, E Brogi, T Nehhozina, M Akram, L Norton, AD Corben. Memorial Sloan-Kettering Cancer Center, New York, NY

Background: Extravasated mucin (EM) in core needle biopsy (CNB) is a worrisome finding and routinely leads to surgical excision (EXC). Because EM alone is uncommon in CNB, data on the excisional findings in cases with only benign or atypical epithelium is limited.
Design: We reviewed CNBs with EM diagnosed between 2000 and 2009 together with the subsequent EXC, with the exclusion of malignant cases. We also collected patient demographic, radiological and follow-up (FU) information. Immunoperoxidase stain for MUC6 was performed on 20 CNBs and 22 EXCs.
Results: We identified 30 patients (pts) with EM on CNB. All pts were women, with median age of 50 yrs (range: 39-78). Calcifications (Ca++) had prompted CNB in 28 pts (93%), and were found in EM in 9 cases, within acini in 23 and in the stroma in 4. The CNB had been done for a mass lesion in 2 pts. The epithelium adjacent to EM was benign (EM-BEN) in 12 cases and atypical (EM-ATP) in 18 (9 ADH, 5 columnar cells with atypia, 2 ALH, 1 atypical apocrine cells, 1 suspicious for carcinoma). Deeper levels had been originally obtained in 8 cases (27%), of which 6 had atypia. EXC of 22 cases (73%) was performed at our center. Only 1 EM-BEN CNB showed rare atypical apocrine cells (AAC) in the EXC, in contrast to 5 EM-ATP that were upgraded to DCIS (4) and mucinous carcinoma (1.3 cm, intermediate nuclear grade). DCIS was solid-cribriform type with mucin (1), cribriform (1), solid (1), and micropapillary (1); nuclear grade was low (3) or intermediate to high (1). EM was present in the biopsy site in 8/22 EXC (36.6%), including 7 with atypical/malignant findings. Two pts with EM-ATP underwent EXC elsewhere and slides were not available for review. The radiological FU of a third patient remained unchanged at 6 months. Three EM-BEN pts were lost to FU, and 2 had benign mammograms at 32 and 33 months. Results of MUC6 stain were noncontributory due to loss of the EM on the deeper sections.

Results of Follow-up Excisions
EM-BEN127/12 (58.3%)1/7 (14.2%)
EM-ATP1815/18 (83.3%)5/15 (33.3%)
TOTAL3022/30 (73.3%)6/22 (27.2%)

Conclusions: The results of our study show that when EM alone is identified in a CNB and the histologic findings correlate with radiology, the EXC is usually benign. In these cases, CNB sampling of the area may suffice. In contrast, EM-ATP in CNB correlates with a more serious lesion in a third of cases and should always warrant excision.
Category: Breast

Wednesday, March 24, 2010 9:30 AM

Poster Session V # 41, Wednesday Morning


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