Ongoing comparison of confocal laser endomicroscopy (PCLE) pulmonary images with surgical biopsies for lung cancer diagnosis

Abstract

<h3>Background</h3> Probe-based confocal laser endomicroscopy (pCLE) is a new FDA approved tool used for in vivo microscopic imaging of proximal and distal airways including bronchial and alveolar walls, microvessels, and inflammatory cells. Light at 488 nm wavelength is focused via a pinhole-sized aperture incorporated into a flexible probe that fits into the working channel of a standard bronchoscope and reflected back through that aperture to produce an image that can aid in the identification of neoplastic processes. Studies have demonstrated elastin and collagen fibers as having endogenous fluorescence by pCLE. No studies have correlated in vivo imaging by pCLE to pathologic samples obtained during bronchoscopy. This combination could prove diagnostically advantageous to both clinician and pathologist. <h3>Design</h3> Selected patients undergoing bronchoscopy from 7/17/ 12 to present are subjected to pCLE followed by biopsy. pCLE and bronchoscopy are performed to help determine abnormal bronchial or alveolar changes that warrant a biopsy. We correlate pCLE images with biopsies obtained during bronchoscopy. Patients ranged from 47 to 82 years of age, and biopsies include adeno, squamous cell, poorly differentiated, small cell and metastatic carcinomas. When necessary, immunohistochemistry (IHC) and electron microscopy (EM) are performed for further tumor classification. Studies are ongoing to add additional tumor types. <h3>Results/findings</h3> By pCLE, differences between normal, inflammation and neoplasia can be recognized. Normal findings consist of organized connective tissue fibers. Inflammatory cells, mostly macrophages, can be recognized within tissue spaces. In neoplastic tissue, a ragged surface can be observed along with disorganization of the collagen/elastin fibers within the bronchi/ alveoli. Differences between squamous (SCC) and adenocarcinomas (ADC) can be suggested on the basis of imaging patterns. SCC shows friability and dense areas of auto fluorescence with dark spots representing tumor groups. ADC shows less fluorescence and gives a mottled appearance to the tissue. ADC with bronchioloalveolar differentiation and a lepidic pattern of growth can be suspected when a studded appearance is noted by pCLE. Disarray of fibers increases with more poorly differentiated carcinomas. Biopsies and pCLE images can be correlated by comparing tissue patterns with images. The use of IHC and ultrastructural evaluation (EM) further support our pCLE and microscopic findings. <h3>Conclusions</h3> pCLE allows the distinction between benign and malignant tissues, assists in obtaining diagnostic tissue, and recognizes tumor growth patterns. Correlation between biopsies and pCLE can help aid sampling and diagnostic techniques. Larger studies can enhance our understanding of how pCLE can help differentiate tumor types.