Unusual histological findings after partial pancreaticoduodenectomy including benign multicystic mesothelioma, adenomyoma of the ampulla of Vater, and undifferentiated carcinoma, sarcomatoid variant: a case series

部分胰十二指肠切除术后罕见组织学发现，包括良性多囊性间皮瘤、乏特壶腹腺肌瘤和未分化癌肉瘤样变异型：病例系列