Bronchoscopic imaging modalities have been developed and applied for detection of abnormalities in bronchial mucosa.1 The recent advances in endoscopic imaging technology have enabled the visualization of cellular structure in vivo. Several investigators had reported in vivo observation of living cancer cells or epithelial cells.2–5
Here, we report a case of endobronchial tumor observed by endocytoscopy. This novel bronchoscopy basically tries to approach in vivo microscopy.
A 68-year-old woman presented with cough and dyspnea in January 2010. Chest x-ray film and computed tomography showed atelectasis in the right upper lobe. She had a history of a bladder neoplasm, which was treated by cystectomy followed by combination chemotherapy. Conventional flexible bronchoscopy revealed a polypoid tumor in the right upper lobe bronchus, protruding into the right main bronchus (Fig. 1A).
We observed the surface of the endobronchial tumor and normal bronchial mucosa by using the endocytoscopy system (Y0004, endoscopy-based type; Olympus Medical Systems Corp., Tokyo, Japan). This novel system showed oval-shaped tumor cells with prominent nuclei on the surface of the tumor with methylene blue dye staining (Fig. 1B). These cells were varied in size and larger as compared with the normal bronchial epithelial cells (Fig. 1C). Pathologically, biopsied specimen of the tumor demonstrated foci of metastatic urothelial carcinoma with squamous cell differentiation (Fig. 2). These cancer cells were similar to the cell images of endocytoscopy system.
In addition, a covered metallic self-expandable stent was placed in the right main to the intermediate bronchus for preventing atelectasis of the right mid and lower lobes after the bronchoscopic examination. The stent was able to dilate the stenosis temporarily.
The endocytoscopy system is established on the basis of contact light microscopy that includes 2 systems: conventional imaging and microscopic imaging system. Microscopic imaging requires contact to the surface of the tumor or bronchial mucosa. The first, we approach to the area of interest in central bronchus by conventional view. The next, we softly attach to the surface of the area and keep contact with it after switching to microscopic imaging. This system visualizes cellular structures on superficial cell layers of endobronchial lumen. Within this system, 400× magnification is achieved on a 14-inch television monitor. The observation depth is approximately 500 μm. Several investigators reported that endoscopy had the potential for in vivo evaluation of cellular atypia or structure atypia in the gastrointestinal tract2–4 and the respiratory tract.5 They stated that endocytoscopy system was useful to distinguish between normal bronchial epithelial cells and dysplastic cells or malignant cells in real time.
In this particular case, we applied this endocytoscopy system to an endobronchial lesion during conventional bronchoscopy. The endocytoscopy system revealed irregularly shaped polymorphic cells on the surface of the tumor with methylene blue dye staining in real time. The nuclei and cytoplasm were stained dark blue and pale blue, respectively. In contrast, approximately equal-sized epithelial cells were arranged regularly on normal bronchial mucosa. The images of endocytoscopy system were thought to correspond with microscopic findings.
Because of the movement caused while breathing, it was difficult to keep the contact of the tip of the bronchoscope to the lesion during microscopic observation. Microscopic images were often blurred by breathing. In addition, the observation site where cardiac pulsation was transmitted was also difficult. Organ motility in respiration and transmission of heart beat might continue to make it difficult to obtain interpretable images.
Areas that were able to contact the tip of the bronchoscope had been limited. The side wall of the bronchus was difficult to bring the tip of endocytoscope into contact with the mucosa in the bronchial lumen. The lesions in the face direction were thought to be preferable for microscopic observation.
The question is whether this technology will result in clinical advancement. Compared with the other bronchoscopic techniques such as narrow band imaging, autofluorescence imaging, optical coherent tomography, and high-magnification bronchoscopy, the endocytoscopy system may offer the advantage of visualizing surface cells in vivo. This technology may have the potential to provide pathologic diagnosis during bronchoscopy.
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