Regionally Metastatic Merkel Cell Carcinoma Associated with Paraneoplastic Anti-N-methyl-D-aspartate Receptor Encephalitis

Merkel Cell Carcinoma

Sophia Z. Shalhout, Kevin S. Emerick, Peter M. Sadow, Jenny J. Linnoila, David M. Miller


September 25, 2020

We present a case of MCC presenting with NMDA Receptor Encephalitis.


Merkel cell carcinoma (MCC) is a rare neuroendocrine cancer most commmonly presenting in the skin and generally associated with sun exposure, immunosuppression, advanced age and the Merkel cell polyomavirus. We present the case of a 59-year-old male with regionally metastatic Merkel cell carcinoma complicated by the paraneoplastic manifestation of anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis. Awareness and detection of paraneoplastic syndromes (PNS) are crucial in the era of immune checkpoint inhibitors (ICI) for advanced MCC, where treatment with immunotherapy has the potential to exacerbate preexisting autoimmune PNS and lead to worsened or even lethal immune-related adverse events.