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Abstract：
BACKGROUND: Pancreatic medullary carcinoma (PMC) is a rare pancreatic tumor, usually showing the presence of microsatellite instability, mostly MLH1 silencing, and a wild-type KRAS mutation status. We report here a PMC arising from a Pancreatic Intraductal Papillary Mucinous Neoplasm (IPMN), both having KRAS and TP53 mutations.
METHODS: We report the case of a 73-year-old woman presenting with right iliac fossa pain. MRI revealed a 16 mm diameter mass in the pancreas, leading to a pancreatic duct stricture and upstream a dilatation of the distal pancreatic duct of Wirsung. A fine needle aspiration was performed, and pathology analysis revealed malignant glandular cells. The patient underwent distal pancreatectomy. Gross examination revealed an12 mm indurated white lesion, adjacent to a cystic lesion extending into the rest of the pancreatic body. Microscopically, the cystic area represented a mixed (gastric-type and pancreatobiliary-type) IPMN, involving the main and secondary pancreatic ducts with low-grade and high-grade dysplasia. In the periphery of this IPMN, a 14mm associated invasive carcinoma was observed, characterized by focal gland formation and by poorly differentiated cells with a syncytial appearance, associated with a dense lymphoplasmocytic and neutrophilic infiltrate. Immunohistochemical analyses showed loss of MSH2 and MSH6 expression. Microsatellite instability was confirmed by molecular test. Molecular analysis was performed both on the invasive carcinoma and on the high-grade dysplasia IPMN, revealing the same mutation profile with KRAS and TP53 mutations. The proposed diagnosis was mixed IPMN with associated invasive medullary carcinoma that presented loss of MSH2 and MSH6 expression.
CONCLUSIONS: The present case reports for the first time, at the best of our knowledge, the coexistence of IPMN lesions and PMC, both having the same molecular alterations. It also describes the second case of PMC with microsatellite instability, MSH2 and MSH6 silenced.
METHODS: We report the case of a 73-year-old woman presenting with right iliac fossa pain. MRI revealed a 16 mm diameter mass in the pancreas, leading to a pancreatic duct stricture and upstream a dilatation of the distal pancreatic duct of Wirsung. A fine needle aspiration was performed, and pathology analysis revealed malignant glandular cells. The patient underwent distal pancreatectomy. Gross examination revealed an12 mm indurated white lesion, adjacent to a cystic lesion extending into the rest of the pancreatic body. Microscopically, the cystic area represented a mixed (gastric-type and pancreatobiliary-type) IPMN, involving the main and secondary pancreatic ducts with low-grade and high-grade dysplasia. In the periphery of this IPMN, a 14mm associated invasive carcinoma was observed, characterized by focal gland formation and by poorly differentiated cells with a syncytial appearance, associated with a dense lymphoplasmocytic and neutrophilic infiltrate. Immunohistochemical analyses showed loss of MSH2 and MSH6 expression. Microsatellite instability was confirmed by molecular test. Molecular analysis was performed both on the invasive carcinoma and on the high-grade dysplasia IPMN, revealing the same mutation profile with KRAS and TP53 mutations. The proposed diagnosis was mixed IPMN with associated invasive medullary carcinoma that presented loss of MSH2 and MSH6 expression.
CONCLUSIONS: The present case reports for the first time, at the best of our knowledge, the coexistence of IPMN lesions and PMC, both having the same molecular alterations. It also describes the second case of PMC with microsatellite instability, MSH2 and MSH6 silenced.
摘要：
背景：胰腺髓样癌（PMC）是一种罕见的胰腺肿瘤，通常显示存在微卫星不稳定性，主要是MLH1沉默，和野生型KRAS突变状态。我们在这里报告了胰腺导管内乳头状黏液性肿瘤（IPMN）引起的PMC，都有KRAS和TP53突变。
方法：我们报告一例73岁女性患者出现右髂窝疼痛。核磁共振显示胰腺有一个直径16毫米的肿块，导致胰管狭窄和Wirsung远端胰管扩张的上游。进行了细针抽吸，病理分析显示为恶性腺细胞。患者接受了远端胰腺切除术。大体检查发现12毫米硬结白色病变，与延伸到胰腺体其余部分的囊性病变相邻。微观上,囊性区域代表混合（胃型和胰胆型）IPMN，累及低度和高度发育不良的主要和次要胰管。在这个IPMN的外围，观察到14mm相关的浸润性癌，以局灶性腺体形成和具有合胞体外观的低分化细胞为特征，伴有密集的淋巴细胞和嗜中性粒细胞浸润。免疫组织化学分析显示MSH2和MSH6表达丧失。分子测试证实了微卫星的不稳定性。对浸润性癌和高级别异型增生IPMN进行分子分析，揭示与KRAS和TP53突变相同的突变谱。建议的诊断是IPMN与相关的浸润性髓样癌混合，表现为MSH2和MSH6表达丧失。
结论：本病例为首次报告，据我们所知,IPMN病变与PMC共存，都有相同的分子变化。它还描述了具有微卫星不稳定性的PMC的第二种情况，MSH2和MSH6沉默。
方法：我们报告一例73岁女性患者出现右髂窝疼痛。核磁共振显示胰腺有一个直径16毫米的肿块，导致胰管狭窄和Wirsung远端胰管扩张的上游。进行了细针抽吸，病理分析显示为恶性腺细胞。患者接受了远端胰腺切除术。大体检查发现12毫米硬结白色病变，与延伸到胰腺体其余部分的囊性病变相邻。微观上,囊性区域代表混合（胃型和胰胆型）IPMN，累及低度和高度发育不良的主要和次要胰管。在这个IPMN的外围，观察到14mm相关的浸润性癌，以局灶性腺体形成和具有合胞体外观的低分化细胞为特征，伴有密集的淋巴细胞和嗜中性粒细胞浸润。免疫组织化学分析显示MSH2和MSH6表达丧失。分子测试证实了微卫星的不稳定性。对浸润性癌和高级别异型增生IPMN进行分子分析，揭示与KRAS和TP53突变相同的突变谱。建议的诊断是IPMN与相关的浸润性髓样癌混合，表现为MSH2和MSH6表达丧失。
结论：本病例为首次报告，据我们所知,IPMN病变与PMC共存，都有相同的分子变化。它还描述了具有微卫星不稳定性的PMC的第二种情况，MSH2和MSH6沉默。
