Anti-KLHL11 encephalitis requires extensive tumor screening as clinical features do not distinguish from malignancyDoctors find patterns in rare brain inflammation from antibodies

Frontiers in Medicine Published September 17, 2026 DOI ↗ Editorial oversight: Dr. Amelia Tan, PhD · Internal Medicine & Chronic Disease

AI-generated summary of the cited source, checked by automated accuracy review. How we work

Key Takeaway

Note that clinical and imaging features cannot distinguish anti-KLHL11 encephalitis from tumor-positive cases.

This systematic review analyzes 13 cases of anti-KLHL11 encephalitis in patients without detectable malignancy. The review synthesizes clinical manifestations, including ataxia (9/13), dysarthria (8/13), and gaze palsy or nystagmus (6/13). Neuroimaging findings were varied, with 7 cases showing T2/FLAIR hyperintensities and 4 showing cerebellar or brainstem atrophy. Laboratory data included a median CSF leukocyte count of 9 x 10^6/L and a median serum anti-KLHL11 antibody titer of 1:100.

Regarding treatment, 6 patients showed clinical improvement with immunotherapy, 3 remained stable, and 4 deteriorated. The authors note that the small sample size of 13 cases limits the ability to draw broad conclusions. They emphasize that these cases cannot be reliably distinguished from tumor-positive cases based solely on clinical symptoms and neuroimaging findings.

Clinical practice relevance is centered on the necessity of comprehensive tumor screening and long-term follow-up for patients presenting with anti-KLHL11 encephalitis. Because clinical and imaging features are not specific enough to rule out underlying malignancy, extensive investigation is required to confirm the absence of a primary tumor.

How this fits prior evidence

This finding addresses a gap in the clinical management of autoimmune encephalitis. While prior evidence notes that diverse therapeutic approaches including immunotherapy are utilized for patients with occult squamous cell carcinoma, this review highlights the specific difficulty in distinguishing anti-KLHL11 encephalitis from cases with underlying malignancy based on clinical and imaging data alone.

When a patient develops sudden brain inflammation, doctors must figure out why. In some cases, the body's own immune system attacks the brain because of specific antibodies, like anti-KLHL11. This condition is tricky because it can look almost identical to brain issues caused by tumors on scans and in clinical symptoms.

A review of 13 cases showed that patients often experienced issues like difficulty speaking, balance problems, and eye movement problems. While some patients improved with immunotherapy, others stayed stable or got worse. The study also noted that two patients sadly died from respiratory failure.

Because the symptoms and imaging are so similar to tumor-related cases, doctors cannot tell the difference based on scans alone. This means patients need thorough screening and long-term follow-up to manage the condition safely. Because the study looked at a small group of 13 people, more research is needed to confirm these findings.

What this means for you:

Anti-KLHL11 brain inflammation looks like a tumor on scans, requiring careful screening and long-term follow-up.

Common questions

How is this condition diagnosed?

It is very difficult to tell this condition apart from cases caused by tumors based only on clinical symptoms or brain scans. Because the symptoms and imaging look so similar, doctors must perform comprehensive tumor screenings and provide long-term follow-up to manage the patient's care.

What are the common symptoms?

Patients often experience ataxia, which is a lack of muscle coordination, and dysarthria, which makes it hard to speak clearly. Other common findings include problems with eye movement or focus, known as gaze palsy or nystagmus.

How do patients respond to treatment?

In a small group of 13 patients, 6 showed clinical improvement with immunotherapy, 3 remained stable, and 4 deteriorated. Because the sample size is small, these results are not enough to predict exactly how every patient will respond.

Study Details

Study typeSystematic review

EvidenceLevel 1

PublishedSep 2026

View Original Abstract ↓

BackgroundAnti-Kelch-like protein 11 (KLHL11) antibody encephalitis, first reported in 2019, is a rare autoimmune disorder typically associated with seminoma. This disorder exhibits a striking male predominance, with cerebellar ataxia as the hallmark manifestation, whereas seizures and altered consciousness occur less frequently. Cases without detectable malignancy account for fewer than 20% of reports, and their clinical manifestations, treatment responses, and outcomes have not been systematically characterized.MethodsWe report a case of a 62-year-old male with anti-KLHL11 encephalitis and no detectable malignancy, who initially presented with recurrent generalized tonic-clonic seizures (GTCS), followed by intermittent seizures and progressive neurological deterioration. A systematic search of published cases with narrative synthesis was conducted to analyze the clinical presentation, neuroimaging features, treatment responses, and outcomes of similar reported cases.ResultsWe analyzed 13 cases of anti-KLHL11 encephalitis without detectable malignancy. The most common clinical manifestations were ataxia (9/13), dysarthria (8/13), and gaze palsy/nystagmus (6/13). Intracranial pressure (ICP) (median: 165 mmH2O, range: 60–200 mmH2O), cerebrospinal fluid (CSF) leukocyte count (median: 9 × 106/L, range: 1–46 × 106/L), and CSF protein level (median: 0.50 g/L, range: 0.27–1.32 g/L) were also measured. The median serum anti-KLHL11 antibody titer was 1:100 (range: 1:30–1:160,000), while CSF anti-KLHL11 antibody titer was 1:10 (range: 1:1–1:32). Electroencephalography (EEG) was normal in 2 cases, showed epileptiform discharges in 2, diffuse background slowing in 2, and sleep-related central hypoventilation in 1. Brain magnetic resonance imaging (MRI) was unremarkable in 3 cases. Seven cases (53.8%) presented with T2/fluid-attenuated inversion recovery (FLAIR) hyperintensities, 4 cases (30.8%) showed cerebellar/brainstem atrophy, 1 case (7.7%) presented with acute cerebral infarction. Following immunotherapy, 6 patients achieved clinical improvement, 3 patients remained clinically stable, 4 deteriorated clinically, of whom 2 died of central respiratory failure.ConclusionAnti-KLHL11 encephalitis without detectable malignancy cannot be reliably distinguished from tumor-positive cases based solely on clinical symptoms and neuroimaging findings. The gold standard for differential diagnosis remains comprehensive tumor screening and long-term follow-up. Extensive white matter and deep gray matter involvement, together with prominent seizures, may be more prevalent in patients without detectable malignancy, although these observations require validation in larger comparative cohorts.

Anti-KLHL11 encephalitis requires extensive tumor screening as clinical features do not distinguish from malignancyDoctors find patterns in rare brain inflammation from antibodies

How this fits prior evidence

Common questions

Study Details

Budesonide-glycopyrronium-formoterol fumarate dihydrate improved lung function and reduced severe exacerbations versus budesonide-formoterol in inadequately controlled asthma

New Asthma Drug Cuts Attacks Without Recent Crisis

Clinical research that matters. Delivered to your inbox.

Anti-KLHL11 encephalitis requires extensive tumor screening as clinical features do not distinguish from malignancyDoctors find patterns in rare brain inflammation from antibodies

How this fits prior evidence

Common questions

More on Anti-KLHL11 antibody encephalitis

Study Details

Budesonide-glycopyrronium-formoterol fumarate dihydrate improved lung function and reduced severe exacerbations versus budesonide-formoterol in inadequately controlled asthma

New Asthma Drug Cuts Attacks Without Recent Crisis

Clinical research that matters. Delivered to your inbox.

Related in Allergy & Immunology

From Other Specialties