P5-11-03: Real-Time Imaging of Human Breast Tissue with Reflectance Confocal Microscopy: Correlation with Routine Pathology

Background: Near-infrared reflectance confocal microscopy (RCM) allows for immediate noninvasive 3-D optical sectioning of opaque objects, such as human tissue, without using the potentially destructive staining and fixing methods used with routine pathology. Recently, RCM has been used to differentiate between malignant and non-malignant dermatologic conditions. We hypothesize that this technique can be used to efficiently and reliably evaluate human breast tissue for the presence of malignancy without compromising the ability to perform routine immunohistochemical (IHC) analyses that accompany the diagnosis of invasive breast cancer.

Methods: 45 core needle breast biopsies (12mmx2mm) were collected under sonographic guidance. Biopsy specimens were immediately placed in phosphate buffered saline, injected with 5% acetic acid to enhance reflectivity of the nuclei, and imaged within 5–10 minutes. Digital images of the nuclear and cellular morphology from each intact specimen were acquired and catalogued within 1 hour of biopsy using the VivaCell 5000. Tissue samples were then formalin-fixed and sectioned for routine H&E evaluation or IHC assays. A board certified pathologist trained on 16 paired RCM images and H&E slides was given the blinded test set created from these 45 breast biopsies and asked to evaluate the RCM images for the presence of carcinoma. Preliminary evaluation was also done on 5 biopsy samples with known estrogen receptor (ER) and progesterone receptor (PR) status to determine the feasibility of assessing ER/PR on tissue treated with acetic acid for RCM.

Results: Routine H&E staining identified invasive carcinoma 10/45 biopsy samples (9 invasive ductal [IDC], 1 invasive lobular [ILC]); 2 specimens with IDC also contained ductal carcinoma in situ (DCIS). Evaluation of the RCM images led to the same diagnosis of invasive carcinoma vs. not in all 45 samples and correctly identified 6/9 IDC and 1/1 ILC. RCM correctly identified 1/2 specimens known to contain DCIS. RCM misclassified 3 IDC as DCIS (1), ILC (1), or lobular carcinoma in situ (1), and 1 DCIS as ILC. With respect to the determination of ER/PR status, RCM accurately assessed positivity for both receptors in all 5 specimens.

Conclusions: RCM is comparable to standard microscopy for the reliable identification of carcinoma, and the ability to evaluate breast tissue for malignancy using this technology allows for real-time pathology and may negate the need for repeat diagnostic biopsies to ensure adequate sampling for diagnosis. Importantly, the ability to perform routine IHC for ER/PR status after tissue processing for RCM appears to be preserved. Further evaluation applying the existing technology to a larger sample size for histopathologic correlation, assessment of ER/PR status, and evaluation for HER2 status are planned. These encouraging findings support interest in tailoring RCM for breast tissue to improve the ability to distinguish between invasive vs. in situ disease, and ductal vs. lobular histology.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-11-03.