Progressive Perivascular Enhancement in KLHL11 Encephalitis: A Case of Delayed Seminoma Recurrence Presenting as Autoimmune Encephalitis
Solomon Nittala1, Nicole Baldwin1, Farhad Mahmoudi1, Kurt Statz-Geary2, Ana Silvia Salazar2, Maria Juliana Borja2, Marijo Bilusic2, Ruham Nasany2, Sebastian Suarez2, Flavia Nelson1
1Neurology, University of Miami, Miller School of Medicine, 2University of Miami, Miller School of Medicine
Objective:
To describe the evolving clinical and radiological features of KLHL11-positive paraneoplastic encephalitis in association with delayed seminoma recurrence.
Background:
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.
Design/Methods:
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.
Conclusions:
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.
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