Significance of in vitro photodynamic cytodiagnosis using 5-aminolevulinic acid in solid pancreatic tumors extracted by endoscopic ultrasound-guided fine-needle aspiration

•Solid pancreatic tumors underwent EUS-FNA, in vitro photodynamic cytodiagnosis using 5-ALA was useful in a judgment of malignancy•In vitro PDCD could safely identify a diagnosis of pancreatic cancer without requiring an expert pathologist.•In two cases, PDCD made it possible to diagnose the malignancy which was difficult to identify a diagnosis of pancreatic cancer by conventional cytodiagnosis. Recently, photodynamic diagnosis using 5-aminolevulinic acid (5-ALA) has gained attention for the diagnosis of neoplastic diseases. In the present study, an in vitro method of photodynamic cytodiagnosis (PDCD) performed using the reagent 5-ALA in the cytodiagnosis of solid pancreatic tumors was developed. Here, we assess the accuracy of PDCD for malignancy. EUS-FNA was performed from September 2015 to March 2018 in patients with solid pancreatic tumors at Osaka Rosai Hospital. Samples were diagnosed independently by an expert pathologist and a medical doctor with conventional cytology and PDCD. A total of 53 patients (35 males, average age: 70.2 years old) were enrolled. The definitive diagnoses were 7 benign lesions and 46 malignant lesions. Using the in vitro PDCD method, the detection of reddish fluorescence in cell samples indicated cancer cells. PDCD had a sensitivity of 91.3% (42/46) and a specificity of 100% (7/7), while conventional cytology had a sensitivity of 93.5% (43/46) and a specificity of 85.7% (6/7). Two patients were successfully diagnosed with malignancy only by the PDCD method. In vitro PDCD performed using the 5-ALA method can effectively and safely identify a diagnosis of pancreatic cancer without requiring an expert pathologist. The sensitivity of this technique could be increased in the diagnosis of pancreatic malignancy by combining it with the conventional method.