Long lasting trigeminal neuropathy, limbic encephalitis and abdominal ganglionitis without primary cancer: An atypical case of Hu-antibody syndrome

Objectives: Anti-Hu antibodies (Hu-Abs) are the most frequent onconeural antibodies associated with paraneoplastic neurologic syndromes (PNS). PNS include a variety of neurological syndromes, affecting less than 1/10,000 patients with cancer. In the majority of cases, PNS will manifest before the malignancy is diagnosed. We found a case in which PNS was diagnosed without finding a primary malignancy after extensive work-up and even post-mortem autopsy.

Patient and methods: We present a case report of a 58-year-old man. This article includes extensive clinical work-up, full-body autopsy and brain autopsy with classical histochemical and myelin stainings and immunohistochemistry was performed.

Results: The patient developed a progressive trigeminal neuropathy over a period of 5 years, in combination with cerebellar degeneration, asymmetrical brainstem and limbic encephalitis. Serum showed repeatedly high anti-Hu antibodies. Comprehensive cancer screening could not demonstrate any primary malignancy. Therapy with corticosteroids, plasma exchange, cyclophosphamide and rituximab showed no beneficial effect. He died from the complications of enteric ganglionitis 5 years after onset of the first symptoms. A postmortem autopsy could not detect a primary malignancy either. Brain morphology is described in detail.

Conclusion: Paraneoplastic anti-Hu encephalitis cases associated with SCLC or other primary neoplasms are well known. An adult with a progressive multifocal neurological syndrome in the presence of positive anti-Hu antibodies, but without any primary neoplasm after a follow-up over 5 years is unusual.