Spectra of well-differentiated neuroendocrine lesions in the extrahepatic biliary system: a case series.

This study highlights the spectrum of extrahepatic biliary well-differentiated neuroendocrine lesions, ranging from incidental microscopic NCMs to grossly apparent mass-forming NETs, potentially requiring different clinical management. Noteworthy is the frequent association of incidental microscopic neuroendocrine cell proliferations with biliary lithiasis, indicating a potential neuroendocrine metaplastic pathogenesis that merits further exploration.