Nuclear Chromatin Heterogeneity in High-Grade PanIN Detected by Serial Pancreatic Juice Aspiration Cytological Examination (SPACE): A Report of Two Cases

Serial pancreatic juice aspiration cytological examination (SPACE) has recently been recognized as a useful method for detecting high-grade pancreatic intraepithelial neoplasia (high-grade PanIN). However, the cytological features of high-grade PanIN are heterogeneous, and some cases remain difficult to diagnose. We examined the cytological findings of two surgically resected cases of high-grade PanIN detected by SPACE. Quantitative image analysis was performed to evaluate nuclear atypia and chromatin heterogeneity. In addition, hyperspectral imaging analysis was conducted in one case to assess intranuclear spectral heterogeneity. Case 1 demonstrated focal high-grade PanIN with relatively mild cytological atypia, whereas Case 2 showed multifocal high-grade PanIN with numerous markedly atypical cells. Despite these differences, both cases shared heterogeneous nuclear chromatin staining within the same epithelial clusters. Image analysis demonstrated significantly increased nuclear area, decreased circularity, decreased mean nuclear brightness, and increased intranuclear brightness standard deviation in Case 2 compared with Case 1, indicating differences in the severity of nuclear atypia. In contrast, overlapping distributions of intranuclear brightness standard deviation were observed in both cases, suggesting shared intranuclear chromatin heterogeneity. Furthermore, hyperspectral imaging analysis demonstrated increased intercellular spectral heterogeneity in high-grade PanIN compared with normal pancreatic ductal epithelium, supporting the presence of chromatin heterogeneity from an optical perspective. Although the cytological appearance of high-grade PanIN varies among cases, nuclear chromatin heterogeneity may represent a common and diagnostically important feature. Image analysis and hyperspectral imaging may provide useful objective approaches for evaluating such heterogeneity.