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Abstract Details

Progressive Perivascular Enhancement in KLHL11 Encephalitis: A Case of Delayed Seminoma Recurrence Presenting as Autoimmune Encephalitis
Autoimmune Neurology
P1 - Poster Session 1 (8:00 AM-9:00 AM)
1-008
To describe the evolving clinical and radiological features of KLHL11-positive paraneoplastic encephalitis in association with delayed seminoma recurrence.
Antibodies to Kelch-like protein 11 (KLHL11) define a rare paraneoplastic encephalitis typically linked to testicular germ cell tumors. It often presents as steroid-responsive rhombencephalitis, but diagnosis may be delayed when tumor recurrence is clinically silent. Recognition of this entity is essential for early immunotherapy and cancer surveillance.

A 42-year-old man with a history of left testicular seminoma status post orchiectomy in 2018 presented with progressive vertigo, diplopia, unsteady gait, and episodic nausea. Brain MRI revealed bilateral symmetrical enhancing lesions involving the inferior vermis and bilateral cerebellar tonsils. Cerebrospinal fluid (CSF) analysis demonstrated an elevated IgG index (1.2) and  all other test negative. He improved after corticosteroids and IVIG but developed new periventricular and leptomeningeal enhancement seven months later. KLHL11-IgG antibodies were detected, prompting oncologic reassessment. FDG-PET revealed para-aortic lymphadenopathy, and biopsy confirmed metastatic seminoma. The patient received rituximab and four cycles of etoposide-cisplatin chemotherapy. Despite oncologic remission, he experienced relapsing neurological decline marked by new linear perivascular enhancement on MRI, resembling GFAP astrocytopathy. Repeat rituximab and ongoing corticosteroids stabilized his symptoms, though he remained wheelchair-dependent with persistent spasticity and ataxia.
N/A
KLHL11-positive paraneoplastic encephalitis should be considered in the differential diagnosis of middle-aged men who present with subacute, steroid-responsive rhombencephalitis, especially those with a history of germ cell tumor, even if clinically in remission. In such cases, early antibody testing and a thorough paraneoplastic evaluation are critical to promptly identify any occult malignancy. Furthermore, this case demonstrates that neurologic sequelae can be persistent and disabling despite successful tumor treatment, underscoring the need for long-term immunomodulatory therapy and rehabilitative support.
Authors/Disclosures
Solomon Nittala, DO
PRESENTER 		Dr. Nittala has nothing to disclose.
Nicole Baldwin, MD Dr. Baldwin has received personal compensation in the range of $500-$4,999 for serving as a volunteer international neurology instructor with CMDA, MAP International, and INMED (NGOs).
Farhad Mahmoudi, MD Dr. Mahmoudi has received personal compensation for serving as an employee of University of Miami.
Kurt Statz-Geary, MD Dr. Statz-Geary has nothing to disclose.
Ana S Salazar, MD Dr. Salazar has nothing to disclose.
Maria J Borja, MD Dr. Borja has nothing to disclose.
MARIJO BILUSIC, MD, PhD The institution of Dr. BILUSIC has received research support from Merck, Inc. The institution of Dr. BILUSIC has received research support from Marengo Therapeutics. The institution of Dr. BILUSIC has received research support from Hookipa Pharma . The institution of Dr. BILUSIC has received research support from Eli Lilly. The institution of Dr. BILUSIC has received research support from Bicycle Therapeutics. The institution of Dr. BILUSIC has received research support from Clasp Therpeutics .
Ruham Alshiekh Nasany, MD Dr. Alshiekh Nasany has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for J&J.
Sebastian Suarez, MD Dr. Suarez has nothing to disclose.
Flavia Nelson, MD (University of Miami, Miller School of Medicine) Dr. Nelson has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Brystol Meyer Squib. Dr. Nelson has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Sanofi. Dr. Nelson has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for TG Therapeutics. Dr. Nelson has received personal compensation in the range of $5,000-$9,999 for serving on a Speakers Bureau for Genetech. The institution of Dr. Nelson has received research support from NIH. Dr. Nelson has received research support from Novartis.