A Case With Longitudinal Changes in Apolipoprotein A2 Isoform Indices Associated With CA19‐9 and MRI Findings Until Pancreatic Cancer Development

An 80-year-old female was referred to our hospital 6 years earlier with an abnormal plasma apolipoprotein A2 isoform (ApoA2-i) index, which is a promising biomarker for pancreatic cancer. Endoscopic ultrasonography (EUS) revealed a single small cystic lesion in the pancreatic head. Subsequently, the patient was followed up regularly. Two years after the initial visit, her ApoA2-i index was 50.2 μg/mL, and her plasma CA19-9 level was 42.5 U/mL. Magnetic resonance cholangiopancreatography (MRCP) performed 3 years after the initial visit also demonstrated small cystic lesions in the pancreatic head, consistent with the findings of the initial EUS, and a signal defect in the main pancreatic duct (MPD) in the pancreatic body, with a normal upstream MPD diameter. Her ApoA2-i index was 52.4 μg/mL, and her plasma CA19-9 level was 42.0 U/mL. Follow-up MRCP indicated similar cystic lesions in the pancreatic head and a signal defect in the MPD in the pancreatic body, with a normal upstream MPD diameter. However, her serial ApoA2-i indices gradually decreased from 52.1 to 35.7 μg/mL, correlated with an increase in plasma CA19-9. The latest MRCP demonstrated a similar signal defect and dilatation of the upstream MPD diameter compared with the previous MPD diameters. Her ApoA2-i index slightly decreased to 35.2 μg/mL, whereas her CA19-9 level remarkably increased to 1320 U/mL. Endoscopic retrograde pancreatography with cytology demonstrated adenocarcinoma cells. In the present case, we observed longitudinal changes in ApoA2-i indices correlated with CA19-9 and MRCP findings.