Shalhout Sophia Z, Emerick Kevin S, Sadow Peter M, Linnoila Jenny J, Miller David M
Division of Hematology/Oncology, Department of Medicine, and Department of Dermatology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA.
Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA 02114, USA.
Case Rep Oncol Med. 2020 Sep 26;2020:1257587. doi: 10.1155/2020/1257587. eCollection 2020.
Merkel cell carcinoma (MCC) is a rare and aggressive cutaneous neuroendocrine cancer with a high risk of recurrence and metastasis. MCC is generally associated with advanced age, fair skin, sun exposure, immunosuppression, and in the majority of cases, the Merkel cell polyomavirus. Neuroendocrine malignancies are associated with a variety of paraneoplastic neurological syndromes (PNS), characterized as autoimmune responses to malignancy-associated expression of neural antigens. Our literature review underscores previous case reports of MCC-associated PNS with voltage-gated calcium channel (VGCC) and anti-Hu (or ANNA-1) autoantibodies. We present the case of a 59-year-old male with regionally metastatic Merkel cell carcinoma complicated by the paraneoplastic manifestation of anti--methyl-D-aspartate receptor (NMDAR) encephalitis. His primary lower neck subcutaneous MCC and metastasis were initially treated with surgery. Additional recurrent lymph node metastases were successfully treated with definitive intensity-modulated radiation therapy. His PNS improved with rituximab therapy. Although rare, this case highlights that in the setting of seizures and prominent psychiatric symptoms accompanying an MCC diagnosis, evaluation for autoimmune paraneoplastic encephalitis is warranted. Awareness and detection of preexisting PNS are crucial in the era of immune checkpoint inhibitors (ICI) for advanced MCC, where treatment with ICI has the potential to exacerbate preexisting autoimmune PNS and lead to worsened or even lethal neurologic immune-related adverse events (nirAEs).
默克尔细胞癌（MCC）是一种罕见且侵袭性强的皮肤神经内分泌癌，复发和转移风险高。MCC通常与高龄、白皙皮肤、阳光暴露、免疫抑制相关，并且在大多数情况下与默克尔细胞多瘤病毒有关。神经内分泌恶性肿瘤与多种副肿瘤性神经综合征（PNS）相关，其特征为对神经抗原的恶性肿瘤相关表达的自身免疫反应。我们的文献综述强调了先前关于MCC相关PNS伴电压门控钙通道（VGCC）和抗Hu（或ANNA-1）自身抗体的病例报告。我们报告一例59岁男性，患有局部转移性默克尔细胞癌，并伴有抗N-甲基-D-天冬氨酸受体（NMDAR）脑炎的副肿瘤表现。他的原发性下颈部皮下MCC和转移灶最初接受了手术治疗。额外的复发性淋巴结转移通过确定性调强放射治疗成功治愈。他的PNS通过利妥昔单抗治疗得到改善。尽管罕见，但该病例强调，在MCC诊断伴有癫痫发作和明显精神症状的情况下，有必要评估自身免疫性副肿瘤性脑炎。在晚期MCC的免疫检查点抑制剂（ICI）时代，认识和检测预先存在的PNS至关重要，因为ICI治疗有可能加重预先存在的自身免疫性PNS，并导致更严重甚至致命的神经免疫相关不良事件（nirAEs）。
