[1737] Biopsy Site Changes in Lung Carcinomas Following Core Needle Biopsy: A Potential Pitfall in the Assessment of Stromal Invasion.

Erika E Doxtader, Sanjay Mukhopadhyay, Anna-Luise Katzenstein. State University of New York Upstate Medical University, Syracuse

Background: Although biopsy site changes are known to cause diagnostic difficulties in thyroid and breast lesions, especially when assessing invasion, such changes have not been noted in the lung. Assessment of invasion is important in lung cancers to separate bronchioloalveolar carcinoma (BAC) from ordinary adenocarcinoma. The aim of this study is to determine whether biopsy related changes occur in the lung and whether they may impact this differential diagnosis.
Design: Lobectomy specimens were examined from patients who had previous core needle biopsies showing adenocarcinoma suggestive of BAC. The presence of biopsy site changes was noted, and the following features were recorded: histologic appearance, size of biopsy site changes, proximity to tumor and presence of entrapped epithelium. The duration since biopsy was also noted.
Results: There were 22 resected adenocarcinomas (14 minimally invasive adenocarcinomas and 8 BACs) with a prior CT-guided core biopsy. Biopsy site changes were identified in 6 of 22 (27%), including 4 minimally invasive adenocarcinomas and 2 BACs. The interval between core biopsy and resection in these 6 cases ranged from 12-35 days (mean, 21). The biopsy site in all 6 cases consisted of an elongated scar composed of collagen and proliferating fibroblasts. Scattered lymphocytes and plasma cells were present in 5 and hemosiderin-laden macrophages in 4. The biopsy scars ranged from 0.8-7.5 mm in length and 0.4-1.7 mm in width. The biopsy site was in close proximity to the tumor in 3 cases, and was partially present within the tumor in the other 3. Benign entrapped lung epithelium was present within the scar in all 6. The 3 cases in which the biopsy site scar was partially within the tumor all contained entrapped malignant epithelium (2 minimally invasive adenocarcinomas and 1 BAC).
Conclusions: Biopsy site related changes can be identified in a significant proportion of lung tumors following core needle biopsy. They need to be distinguished from tumor related stromal reactions that are considered an indication of invasion and are important in the differentiation of BAC and well differentiated adenocarcinoma.
Category: Pulmonary

Tuesday, March 1, 2011 1:00 PM

Poster Session IV # 278, Tuesday Afternoon

 

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