Fluorescence cytology during EUS-FNA

Dr. IkeuraTsukasa Ikeura, MD, PhD, from the Third Department of Internal Medicine, Kansai Medical University, Osaka, Japan shares this New Methods article titled “Fluorescence cytology with 5-aminolevulinic acid in EUS-guided FNA as a method for differentiating between malignant and benign lesions (with video).”

5-aminolevulinic acid (ALA), a photosensitizer, is metabolized into protoporphyrin IX (PpIX) in the mitochondria. ALA is characterized by excessive intracellular accumulation in cancer cells when administered to patients. Since PpIX emits a typical red fluorescence when excited by irradiation with blue-violet light, cancer cells can be identified by detecting red fluorescence. In various organs, photodynamic diagnosis using ALA has been reported as a useful method not only in differentiating between malignant and benign lesions but also in identifying viable tumor margins during surgery. In this study, we examined the diagnostic accuracy of fluorescence cytology with ALA during EUS-guided FNA for abdominal mass lesions.

Twenty-eight patients were included in this study. The final diagnoses of 28 patients were as follows: pancreatic cancer in 21 patients, autoimmune pancreatitis in 4, malignant lymphadenopathy in 1, serous cystadenoma in 1, and benign lymphadenopathy in 1. All patients were orally administered 1 g of ALA 3-6 hours before EUS-guided FNA. The specimens obtained via EUS-guided FNA were evaluated as fluorescence cytology by a gastroenterologist using fluorescence microscopy equipped with special filters to detect PpIX emission. Fluorescence cytology was considered positive if clusters of strong red fluorescence were detected under blue-violet light. In contrast, fluorescence cytology was considered negative if vague or no red fluorescence was observed.

Figure 1
Figure 2. Fluorescence cytology in a patient with pancreatic cancer. A, Fluorescence cytological examination shows red fluorescence induced by the photosensitized emission of protoporphyrin IX (PpIX). B, The corresponding section stained by using the Diff-Quik method shows cancer cells. C, Merge of fluorescence cytology–positive cells and cancer cells in the same sections is shown.

Fluorescence cytology could correctly discriminate between benign and malignant lesions in all patients. No severe adverse reaction of ALA was observed.

Fluorescence cytology with ALA enables a nonpathologist to differentiate between benign and malignant lesions easily, quickly, and correctly.

Rapid on-site evaluation (ROSE) during EUS-guided FNA has been reported to enhance the diagnostic accuracy of EUS-guided FNA in the gastrointestinal tract and in pancreatic tumors; however, ROSE is unavailable because of a shortage in manpower. During EUS-FNA, fluorescence cytology with ALA can become an alternative method to ROSE.

Read the abstract of this article online.

The information presented in Endoscopedia reflects the opinions of the authors and does not represent the position of the American Society for Gastrointestinal Endoscopy (ASGE). ASGE expressly disclaims any warranties or guarantees, expressed or implied, and is not liable for damages of any kind in connection with the material, information, or procedures set forth.

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