Neuronal intermediate filament neurologic autoimmunity in a patient with Merkel cell carcinoma receiving pembrolizumab.
4 affiliations
- 1Department of Neurology, Saint Louis University Hospital, Saint Louis, MO, USA. [email protected].
- 2Department of Hematology and Oncology, Rosalind Franklin University, Chicago , IL, USA.
- 3Cancer Care Specialists of Illinois, O'Fallon, IL, USA.
- 4Department of Neurology, Saint Louis University Hospital, Saint Louis, MO, USA.
Abstract
Background
Neuronal intermediate filament (NIF) autoimmunity is an uncommon paraneoplastic neurologic syndrome that has increasingly been recognized in association with immune checkpoint inhibitor (ICI) therapy. Merkel cell carcinoma is among the malignancies most frequently associated with NIF antibodies, although reported cases remain limited.Case presentation
A 55-year-old female with stage IIIA Merkel cell carcinoma developed vertigo, gait instability, dysarthria, and persistent right hemifacial and cervical spasms after receiving second dose of pembrolizumab for recurrent disease. Brain MRI was unremarkable, while continuous electroencephalography demonstrated encephalopathy without a definitive electrocerebral correlate, raising suspicion for subcortical myoclonus. Cerebrospinal fluid (CSF) analysis revealed lymphocytic pleocytosis, elevated protein. CSF and positive NIF antibodies using cell-based assay. Pembrolizumab was discontinued, and the patient was treated with high-dose corticosteroids followed by monthly intravenous immunoglobulin, resulting in near complete resolution of her neurologic symptoms after 6 months.Conclusion
This case expands the growing spectrum of ICI-associated NIF paraneoplastic neurologic autoimmunity complicating Merkel cell carcinoma. To our knowledge, persistent hemifacial and cervical spasm has rarely been reported in this clinical setting. Early recognition of this syndrome, prompt antibody testing, discontinuation of ICI therapy, and initiation of therapy may improve neurological outcomes while informing further oncologic management.
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BibTeX
@article{hijazi2026neuronal,
title = {{Neuronal intermediate filament neurologic autoimmunity in a patient with Merkel cell carcinoma receiving pembrolizumab.}},
author = {Ali Hijazi and Saffet Guleryuz and Mark A Walshauser and Ghazala Hayat and Maithreyi Chappidi},
journal = {Neurological sciences : official journal of the Italian Neurological Society and of the Italian Society of Clinical Neurophysiology},
year = {2026},
month = oct,
doi = {10.1007/s10072-026-09500-8},
url = {https://europepmc.org/article/MED/42909667},
note = {CC BY},
}
RIS
TY - JOUR
TI - Neuronal intermediate filament neurologic autoimmunity in a patient with Merkel cell carcinoma receiving pembrolizumab.
AU - Ali Hijazi
AU - Saffet Guleryuz
AU - Mark A Walshauser
AU - Ghazala Hayat
AU - Maithreyi Chappidi
PY - 2026
DA - 2026/10/23
JO - Neurological sciences : official journal of the Italian Neurological Society and of the Italian Society of Clinical Neurophysiology
DO - 10.1007/s10072-026-09500-8
UR - https://europepmc.org/article/MED/42909667
AB - Background Neuronal intermediate filament (NIF) autoimmunity is an uncommon paraneoplastic neurologic syndrome that has increasingly been recognized in association with immune checkpoint inhibitor (ICI) therapy. Merkel cell carcinoma is among the malignancies most frequently associated with NIF antibodies, although reported cases remain limited.Case presentation A 55-year-old female with stage IIIA Merkel cell carcinoma developed vertigo, gait instability, dysarthria, and persistent right hemifacial and cervical spasms after receiving second dose of pembrolizumab for recurrent disease. Brain MRI was unremarkable, while continuous electroencephalography demonstrated encephalopathy without a definitive electrocerebral correlate, raising suspicion for subcortical myoclonus. Cerebrospinal fluid (CSF) analysis revealed lymphocytic pleocytosis, elevated protein. CSF and positive NIF antibodies using cell-based assay. Pembrolizumab was discontinued, and the patient was treated with high-dose corticosteroids followed by monthly intravenous immunoglobulin, resulting in near complete resolution of her neurologic symptoms after 6 months.Conclusion This case expands the growing spectrum of ICI-associated NIF paraneoplastic neurologic autoimmunity complicating Merkel cell carcinoma. To our knowledge, persistent hemifacial and cervical spasm has rarely been reported in this clinical setting. Early recognition of this syndrome, prompt antibody testing, discontinuation of ICI therapy, and initiation of therapy may improve neurological outcomes while informing further oncologic management.
SN - 1590-1874
SN - 1590-3478
ER -