嫌疑将主胰管与总胆管连接于主十二指肠乳头（MDP）可能使猫容易患上“三联炎”临床综合征。然而，在患有或未患有三联炎的猫中，MDP的显微解剖或MDP是否存在病变尚未评估。本研究的目的是描述猫MDP的组织形态学特征，并确定MDP解剖学/疾病与胆道、胰腺或肠道炎症或肿瘤的关联。对124只客户的猫进行了术后尸检，对MDP、十二指肠、空肠、回肠、肝脏和胰腺进行了组织学评估。大多数病例（104/124，84%）在MDP处有复杂的管网，胰腺与总胆管之间无区别。MDP处淋巴细胞聚集常见（63/124，51%）。MDP的炎症（MDP炎）出现在124只猫中的35只（28%），通常与胆管炎、胰腺炎或肠炎同时发生（32/35,91%），但仅与肠炎相关（19/35,54%，P < .05）。三联炎较少见（19/124，15%），但与MDP区解剖连接（19/19，100%，P < .05）和MDP炎（12/19，63%，P < .05）相关。124只猫中37只（29%）出现肿瘤，其中以淋巴瘤（28/37，78%）为主。肠病相关的T细胞淋巴瘤2型（EATL2）最常见（n = 16/37，43%），与三联炎和MDP炎相关（P < .05）。这些发现表明MDP的解剖、免疫活化和/或炎症可能在三联炎的发病机制中起作用。需要进一步研究三联炎、MDP炎和EATL2之间的关系。

Conjoining of the major pancreatic duct and common bile duct at the major duodenal papilla (MDP) is suspected to predispose cats to the clinical syndrome of "triaditis." However, microanatomy of the MDP or presence of lesions at the MDP has not been assessed in cats with or without triaditis. The aims of this study were to characterize feline MDP histomorphology and to identify associations between MDP anatomy/disease and the presence of biliary, pancreatic, or intestinal inflammation or neoplasia. Histologic assessment was prospectively performed on the MDP, duodenum, jejunum, ileum, liver, and pancreas from 124 client-owned cats undergoing postmortem examination. The majority of cats (104/124, 84%) had a complex ductular network at the MDP, with no distinction between pancreatic and common bile ducts. Lymphoid aggregates at the MDP were common (63/124, 51%). Inflammation of the MDP (MDPitis) was present in 35 of 124 cats (28%) and was often concurrent with cholangitis, pancreatitis, or enteritis (32/35, 91%), but was only associated with enteritis (19/35, 54%, P < .05). Triaditis was less common (19/124, 15%), but was associated with both conjoined MDP anatomy (19/19, 100%, P < .05) and MDPitis (12/19, 63%, P < .05). Neoplasia was present in 37 of 124 cats (29%), with lymphoma (28/37, 78%) predominating. Enteropathy-associated T-cell lymphoma type 2 (EATL2) was most common (n = 16/37, 43%) and was associated with triaditis and MDPitis (P < .05). These findings suggest that anatomy, immune activation, and/or inflammation of the MDP may play a role in the pathogenesis of triaditis. Further studies are needed to elucidate the relationships between triaditis, MDPitis, and EATL2.