Liu Louisa, Kaur Simmer, Dayyani Farshid, Cho May, Ran-Castillo Dani, Chong Esther, Khandelwal Keerti, Demisse Rahel
Department of Internal Medicine, University of California, Riverside School of Medicine, Riverside, California, USA.
Department of Medical Oncology/Hematology, Loma Linda University Medical Center, Loma Linda, California, USA.
J Gastrointest Oncol. 2023 Apr 29;14(2):1149-1154. doi: 10.21037/jgo-22-755. Epub 2023 Mar 6.
Medullary carcinoma (MC) is a recognized histologic subtype of colorectal cancer characterized by poor glandular differentiation and intraepithelial lymphocytic infiltrate. However, MC originating from the small intestine is exceedingly rare, with only nine cases described in the literature. Based on previous cases, surgical resection is currently the mainstay of treatment for those with localized disease. We report the first case of a patient who presented with unresectable microsatellite instability-high (MSI-H) MC of the duodenum and was instead treated with pembrolizumab.
A 50-year-old man with history of adenocarcinoma of the proximal descending colon status post hemicolectomy and adjuvant treatment with chemotherapy and family history of Lynch syndrome presented with abdominal pain for two weeks. Computed tomography (CT) abdomen/pelvis revealed a 10.7 cm by 4.3 cm mass in the mid-portion of the duodenum abutting against the pancreatic head. Esophagogastroduodenoscopy (EGD) demonstrated circumferential, partially obstructing, intrinsic stenosis of the duodenum with ampullary involvement and likely invasion into the pancreatic head and common bile duct. Endoscopic biopsy of the primary tumor revealed poorly differentiated MC. Immunohistochemical staining showed loss of MLH1 and PMS2 expression. Staging with CT chest showed no evidence of disease. Positron emission tomography (PET) scan redemonstrated circumferential duodenal wall thickening and hypermetabolic activity with standardized uptake value (SUV) max of 26.4, as well as PET-avid epigastric, retroperitoneal, and periaortic lymphadenopathy suggestive of metastasis. He was started on pembrolizumab and found to have stable disease on repeat imaging along with significant improvement in symptoms and performance status.
Due to the rarity of the tumor, there is no standardized approach to treatment. All patients in previously published cases underwent surgical resection. However, our patient was deemed a poor surgical candidate. Given his previous history of colon cancer and treatment with platinum-based therapy, he qualified for pembrolizumab as first line therapy for his MSI-H tumor. To our knowledge, this is the first report of MC of the duodenum as well as the first MC to be treated with pembrolizumab in the first line setting. In order to corroborate the use of immune checkpoint inhibitors as a treatment option for MC of the colon or small intestine, the aggregation of existing and future case data in this unique patient group is certainly warranted.
髓样癌（MC）是一种公认的结直肠癌组织学亚型，其特征为腺管分化差和上皮内淋巴细胞浸润。然而，起源于小肠的MC极为罕见，文献中仅描述了9例。根据既往病例，手术切除目前是局限性疾病患者的主要治疗方法。我们报告了首例十二指肠不可切除的微卫星高度不稳定（MSI-H）MC患者，该患者接受了帕博利珠单抗治疗。
一名50岁男性，有降结肠近端腺癌病史，接受过半结肠切除术及化疗辅助治疗，有林奇综合征家族史，出现腹痛两周。腹部/盆腔计算机断层扫描（CT）显示十二指肠中部有一个10.7 cm×4.3 cm的肿块，紧邻胰头。食管胃十二指肠镜检查（EGD）显示十二指肠有环形、部分阻塞性的固有狭窄，累及壶腹，可能侵犯胰头和胆总管。原发肿瘤的内镜活检显示为低分化MC。免疫组化染色显示MLH1和PMS2表达缺失。胸部CT分期显示无疾病证据。正电子发射断层扫描（PET）扫描再次显示十二指肠壁环形增厚和代谢活性增高，标准化摄取值（SUV）最大值为26.4，以及PET显影的上腹部、腹膜后和主动脉旁淋巴结肿大，提示转移。他开始接受帕博利珠单抗治疗，复查影像学检查发现疾病稳定，症状和体能状态有显著改善。
由于该肿瘤罕见，尚无标准化的治疗方法。既往发表病例中的所有患者均接受了手术切除。然而，我们的患者被认为不适合手术。鉴于他既往有结肠癌病史且接受过铂类治疗，他符合使用帕博利珠单抗作为其MSI-H肿瘤一线治疗的条件。据我们所知，这是十二指肠MC的首例报告，也是首例在一线治疗中接受帕博利珠单抗治疗的MC。为了证实免疫检查点抑制剂作为结肠或小肠MC治疗选择的应用，无疑有必要汇总该独特患者群体中现有和未来的病例数据。
