Paraneoplastic Encephalitis Presenting with Focal Status Epilepticus Associated with Thymoma and CSF CRMP-5 IgG: A Case Report
Objective:
To understand the importance of considering thymoma‑associated paraneoplastic encephalitis in adults with new‑onset focal status epilepticus.
Background:
Paraneoplastic neurological syndromes (PNS) are immune‑mediated disorders triggered by malignancy. Thymoma is a recognized cause of central nervous system autoimmunity, with reported associations to both cell-surface antibodies (e.g., LGI1/CASPR2) that often respond to first‑line immunotherapy and intracellular/onconeural antibodies (e.g., CRMP‑5/CV2) that are typically T‑cell–mediated and carry different prognostic and treatment implications.
Design/Methods:
A 72‑year‑old woman presented with focal status epilepticus (left face/arm/leg jerking) and expressive aphasia. MRI demonstrated progressive, bilateral cortical/subcortical T2/FLAIR abnormalities confined to the supratentorial brain. EEG showed frequent left temporal LPDs. CSF revealed CRMP‑5 IgG (1:128) with otherwise unremarkable routine parameters; CSF infectious PCR incidentally detected Epicoccum nigrum. Mediastinal imaging disclosed a partially calcified anterior mediastinal mass favoring thymoma. Brain biopsy showed reactive astrogliosis/microgliosis, perivascular T‑lymphocytes, and neuronal loss, supporting autoimmune/paraneoplastic encephalitis. The patient received high‑dose IV methylprednisolone and IVIG; antiseizure therapy controlled ictal activity. She remains hospitalized pending surgical resection and antibody confirmation (serum LGI1 pending).
Results:
In adults with new‑onset focal status epilepticus and a mediastinal mass, thymoma‑associated paraneoplastic encephalitis should be considered; paired CSF/serum paraneoplastic panels (including CRMP‑5) should be obtained. For intracellular/onconeural antibodies (e.g., CRMP‑5), tumor resection is often the pivotal therapy; immunotherapy responses may be partial/delayed. Thymoma‑associated encephalitis can show multifocal supratentorial cortical/subcortical MRI lesions beyond the limbic system (consider TAPE pattern). Metagenomic CSF positives for environmental molds (e.g., Epicoccum) require clinical correlation to avoid overtreatment.
Conclusions:
This case underscores the importance of considering thymoma‑associated paraneoplastic encephalitis in adults with new‑onset focal status epilepticus and progressive cortical/subcortical MRI lesions and highlights the diagnostic value of paired testing. Early recognition, prompt immunotherapy, and timely thymectomy are central to optimizing outcomes.
Generative AI Usage
No, did not use generative AI in the drafting or editing in this abstract.
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