Paraneoplastic limbic encephalitis cured with nephron-sparing surgery in a patient with clear cell renal cell carcinoma: a case report

Paraneoplastic NMDA encephalitis, a case report and an extensive review of available literature

Anti-N-methyl-D-aspartate receptor (NMDAr) encephalitis is a prevalent autoimmune condition marked by diverse neuropsychiatric symptoms, primarily impacting young females. The exact mechanisms underlying the development of NMDAr encephalitis have not been fully elucidated. Nonetheless, studies have demonstrated that auto-antibodies targeting the NR1-NR2 subunits of the NMDAr can trigger receptor dysfunction within the central nervous system, thus giving rise to the associated symptoms. Notably, an association exists between NMDAr encephalitis and an underlying neoplastic condition, with approximately 38% of cases exhibiting this paraneoplastic relationship with ovarian teratomas being the most commonly associated malignancy. While the association between NMDAr encephalitis and renal cell carcinoma (RCC) is exceedingly rare. This case report presents the clinical scenario of a 20-year-old female patient diagnosed with NMDAr encephalitis in conjunction with RCC discovered incidentally on a CT abdomen and pelvis performed to rule out an ovarian teratoma. The presented case underscores the importance of adopting a multidisciplinary approach in the diagnosis and treatment of NMDAr encephalitis, particularly when it is linked to an underlying malignancy. Furthermore, it emphasizes the significance of expanding our understanding of the molecular pathogenesis of NMDAr encephalitis to enhance patient care and optimize clinical outcomes. Additionally, a comprehensive review of the existing literature is included, summarizing all reported malignancies associated with NMDAr encephalitis.

Herpes simplex virus-1 encephalitis secondary to whole brain radiation therapy for metastatic renal cell carcinoma

Herpes simplex virus-1 (HSV-1) infection is the most common cause of encephalitis. This virus commonly lays dormant in neural ganglia, specifically the trigeminal ganglia, following retrograde axonal transport from the site of infection. States of immunosuppression can activate the virus to cause active infection. There are several causes of immunosuppression that can cause viral reactivation. Sporadic case reports have demonstrated HSV-1 encephalitis following brain radiotherapy, although no clear relationship between this treatment and HSV-1 encephalitis has been elucidated. HSV1 encephalitis that arises during immunocompromized states has an atypical presentation for encephalitis, potentially obfuscating the diagnosis and delaying subsequent treatment. The main diagnostic criteria, including CSF analysis, brain imaging, and clinical presentation, all commonly present atypically during states of immunosuppression. For these reasons, it is imperative for physicians to be aware of this rare sequelae in appropriate populations, such as patients undergoing brain radiotherapy. We present a case of an atypical presentation of HSV-1 encephalitis in a patient who recently completed radiotherapy for brain metastases secondary to renal cell carcinoma.

Evaluation of the Updated Diagnostic Criteria for Paraneoplastic Neurologic Syndromes in China

Background

Recently, the paraneoplastic neurologic syndrome (PNS) diagnostic criteria have received a major update with a new score system over the past 16 years. We aimed to evaluate the diagnostic performance and clinical utility in China.

Methods

An eligible cohort of 113 Chinese patients diagnosed with PNSs from the Second Affiliated Hospital School of Medicine Zhejiang University and published data were enrolled retrospectively. Data including clinical phenotype, antibody type, the presence of cancer, and duration of follow-up were reviewed and re-evaluated to classify the diagnostic levels for the 2004 and 2021 PNS criteria. The performances of these 2 criteria were compared. The critical parameters of antibody and cancer for the updated criteria were further explored.

Results

The cohort consisted of 69 males and 44 females with a median age of 60 years. Limbic encephalitis (23, 20.4%), anti-Hu antibody (32, 28.3%), and small-cell lung cancer (32, 28.3%) were the most common clinical phenotype, detected antibody, and concomitant cancer, respectively. A total of 97 (85.8%) patients were diagnosed with definite PNS according to the 2004 criteria: only 42.3% (41/97) fulfilled the 2021 criteria, while the remaining 40, 14, and 2 re-diagnosed with probable PNS, possible PNS, and non-PNS. The requirement of cancers consistent with antibody and phenotype increased the specificity and thus greatly enhanced the accuracy of the 2021 criteria.

Conclusion

The updated criteria for PNS emphasized the consistency between cancer phenotype and antibody and showed a better diagnostic value. A better diagnostic yield could benefit disease management.

Paraneoplastic encephalitis associated with renal cell carcinoma

Purpose

Paraneoplastic encephalitis is autoimmune encephalitis accompanied by tumors. Renal cell carcinoma (RCC) is a kidney cancer originating from various types of renal cells and rarely has been associated with paraneoplastic neurologic manifestation. We identified a case series of paraneoplastic encephalitis-associated RCC.

Methods

From a prospective institutional cohort, we identified autoimmune encephalitis patients with RCC. The association between RCC and encephalitis was determined by the following criteria: (1) possible autoimmune encephalitis according to the operational autoimmune encephalitis diagnostic criteria and (2) RCC simultaneously diagnosed with neurological manifestation of encephalitis.

Results

A total of three patients presented encephalitis accompanied by RCC. Two patients had clear cell RCC, and one had chromophobe RCC. All patients showed limbic encephalitis with cognitive decline, memory impairment, or seizure. Brain magnetic resonance imaging showed T2 hyperintensities at the mesial temporal lobe in two patients with clear cell RCC but no remarkable findings in one patient with chromophobe RCC. While one patient who had early surgery within one month of RCC onset had a favorable response to the treatment, the other two patients showed a partial response and a detrimental result.

Conclusion

Paraneoplastic encephalitis associated with RCC presented as limbic encephalitis and was responsive to immunotherapy combined with tumor resection. As our cases identified, RCC should be considered as a cause of seronegative autoimmune encephalitis.