Testicular cancer-associated paraneoplastic encephalitis
Clinical cases: Neurology
Background
A 44-year-old man presents with right-sided tinnitus and sensorineural hearing loss, and within five months of initial hearing changes, he develops double vision and gait instability. Clinical examination shows spontaneous left-beating torsional nystagmus in his primary gaze, down-beating nystagmus in his leftward gaze, and right-beating torsional nystagmus in his rightward gaze. In addition, bilateral asymmetric hearing loss (right greater than left) and ataxic gait are evidenced.
Although his brain MRI was unremarkable, cerebrospinal fluid (CSF) analysis demonstrates lymphocytic pleocytosis and increased protein concentration. Serum and CSF autoantibody evaluations reveal a unique “sparkles” immunofluorescence staining pattern, which is confirmed to be Kelch-like protein 11 (KLHL11) IgG. Scrotal ultrasound reveals microlithiasis, but no testicular tumor is found. A mediastinal mass, however, is identified through whole-body positron emission tomography. The mass is resected with histopathology consistent with seminoma.
The patient was diagnosed with a paraneoplastic anti-KLHL11 rhombencephalitis with a mediastinal seminoma. Following a long course of pulse doses of intravenous solumedrol and oral cyclophosphamide, the patient improves.
Teaching points
- Paraneoplastic cochleovestibulopathy (hearing loss, tinnitus, and/or vertigo) can be the presenting feature of KLHL11 IgG-associated paraneoplastic autoimmunity, which can precede diplopia or ataxia.
- The Mayo Clinic Neuroimmunology Laboratory’s continuously expanding test menu includes novel and clinically useful biomarkers, such as KLHL11 IgG.
Learn more about how our movement disorders testing can help diagnose testicular cancer-associated paraneoplastic encephalitis.
