Anti-Ma1/Ma2 paraneoplastic neurological syndrome associated with malignant mesothelioma: a case study

Our plain-English summary of Anti-Ma1/Ma2 paraneoplastic neurological syndrome associated with malignant mesothelioma: a case study, by A. Mousapasandi, S. Evans, G.T. Kwon (BMJ Neurology Open, 2026).

The study

• Authors: A. Mousapasandi, S. Evans, G.T. Kwon
• Journal: BMJ Neurology Open
• Published: 2026;8(2):e001323
• Read it: PubMed · Publisher · Free full text

Abstract

Introduction: Anti-Ma1/Ma2 paraneoplastic neurological syndromes (PNS) are rare immune-mediated disorders classically associated with testicular germ cell tumours but increasingly recognised in a broader range of malignancies.

Methods: We report a 74-year-old left-handed man who presented with progressive gait ataxia. MRI of the brain showed T2 hyperintensity in the right amygdala and hippocampus, as well as in the left caudate head. Serum and cerebrospinal fluid tested positive for anti-Ma1/Ma2 antibodies. Despite extensive screening, no malignancy was identified.

Results: Neurological deficits worsened over 2 months, including worsening gait, ataxia, opsoclonus and left arm weakness. High-dose corticosteroids, intravenous immunoglobulin, mycophenolate and rituximab led to modest clinical improvement. 4 months later, the patient re-presented with insidious respiratory distress due to a right pleural effusion. Pleural biopsy confirmed mesothelioma. Anti-Ma1/Ma2 PNS linked to mesothelioma are rare but have been reported.

Conclusions: For this rare association, previous few cases described neurological symptoms emerging months to years after a mesothelioma diagnosis, while ours is the first to report symptoms preceding diagnosis. Early immunosuppression can provide temporary clinical benefit. A more sustained benefit requires identification and treatment of the underlying malignancy. This case underscores the importance of ongoing surveillance for malignancy in patients with PNS.

Copyright © Author(s) (or their employer(s)) 2026. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ Group.

In plain English

This short report described one patient: a 74-year-old left-handed man seen in a neurology clinic after 3 months of worsening difficulty walking and some lapses in short-term memory. He had previous asbestos exposure with no diagnosed complications, and a history of smoking. Two months later, while in hospital for a cat bite, his condition worsened, with new abnormal eye movements (opsoclonus), worse unsteadiness and weakness in his left arm. Brain MRI showed abnormal signal in the right amygdala and hippocampus and the left caudate head. His blood and spinal fluid contained anti-Ma1/Ma2 antibodies, which are linked to paraneoplastic neurological syndromes, immune disorders that arise indirectly from cancer. Tumour markers, CT scans and a PET scan found no cancer. Immune treatments gave only partial improvement. About 4 months after he first presented with his neurological symptoms, he developed breathing symptoms from a pleural effusion, and a pleural biopsy showed mesothelioma. The authors concluded that, to their knowledge, this was the first case in which this syndrome was diagnosed before mesothelioma, and that it showed the importance of ongoing surveillance for cancer.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: case report (short report of a single patient)
• Who was studied: One 74-year-old left-handed man seen at a neurology outpatient clinic with 3 months of progressive gait difficulty. The article does not state where or when he was seen.
• Exposure: Previous asbestos exposure, with no diagnosed complications. Fiber type, job and amount of exposure are not given. The patient also had a history of smoking.
• Main results:
  • Two months after the first clinic visit, during a hospital admission for a cat bite, the patient's neurological status deteriorated, with new opsoclonus, worsening gait ataxia and left upper limb weakness.
  • Brain MRI showed T2/FLAIR signal hyperintensity in the right amygdala and hippocampus and in the left caudate head.
  • Serum and cerebrospinal fluid tested positive for anti-Ma1/Ma2 antibodies.
  • An extensive search for cancer (tumour markers, CT scans of the neck, chest, abdomen and pelvis, and an FDG-PET scan) initially found no malignancy.
  • The patient was treated with intravenous methylprednisolone then oral prednisolone, monthly intravenous immunoglobulin, mycophenolate and eventually rituximab. The authors described the initial immunotherapy as giving only partial improvement in symptoms.
  • Approximately 4 months after his initial presentation with neurological symptoms (he had already had 3 months of gait difficulty at that presentation), the patient developed respiratory symptoms.
  • The respiratory symptoms were due to a pleural effusion, and the patient was diagnosed with mesothelioma after a pleural biopsy.
• The authors' conclusion: The authors concluded that, to their knowledge, this was the first case in which anti-Ma1/Ma2 paraneoplastic neurological syndrome was diagnosed before mesothelioma. They said the case illustrates the importance of ongoing surveillance for cancer, including rare cancers not commonly associated with paraneoplastic syndromes.

Topics

Medical terms in this study, explained in our Lexicon: Mesothelioma, Pleural Effusion, Pleural Biopsy.

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