Endoscopic Auto Fluorescence Imaging Is Useful for Detecting Colonic Small Lesions of Lymphoma Resembling Lymphoid Hyperplasia

Abstract

Backgroud and Aim: Detection of colonic lesions of malignant lymphoma is important for staging of the disease, but is particularly difficult, because such a lesion is small and is macroscopically similar to lymphoid hyperplasia by conventional endoscopy and the pathological feature of biopsied specimen of the lesion sometimes resembles each other. Auto-Fluorescence (AF) imaging is a novel endoscopic procedure, which can detect the AF emitted from interstitial collagens in mucosa and submucosal layer, and can provide new information on fibrous structure of the tissue in a real-time fashion. Therefore, we propose that AF imaging would be more effective for the detection and diagnosis of colonic lesions of malignant lymphoma, especially small one, which resembles lymphoid hyperplasia by a conventional endoscopy.Patients and Methods: AF images obtained from 42 colonic lesions in 14 patients with primary intestinal or systemic lymphoma were evaluated as three predominant color strengths; green, purple and blended, depending on the AF reflection. In addition, the strength of AF imaging was quantified by using the software by calculating the fluorescence/reflex (F/R) ratio. The relationships between AFI images (predominant color) or F/R ratio, and histological diagnosis of biopsy specimens obtained from the area were compared retrospectively. Results: All normal mucosa showed “green area” and high F/R ratio. Lymphoid hyperplasia revealed “weak purple spots in green area”, while lymphoma lesion showed “strong purple spots”. The mean F/R ratio of lymphoma was 0.63, significantly lower than those of lymphoid hyperplasia (0.99) (P<0.001), suggesting that AF imaging is useful in discriminating lymphoma from benign lymphoid hyperplasia. When defining the cut-off value of F/R ratio as being 0.71, the sensitivity, specificity and over all accuracy that predicts the lymphoma is 77.8%, 84.8% and 83.3%, respectively.Conclusion: AF imaging by colonoscopy provides benefits in detecting colonic lesions of malignant lymphoma of intestinal or systemic lymphoma and in making differentiation from benign lymphoid hyperplasia. AF imaging might contribute to recognize the slight changes due to intestinal lymphoma, leading us to appropriate therapeutic strategy for either GI or systemic lymphoma.