A clinicopathological study of a patient with anti-Hu-associated paraneoplastic sensory neuronopathy with multiple cranial nerve palsies

Only a few cases of paraneoplastic neurologic syndrome with multiple cranial palsies have been reported. This is the case report of a patient with small-cell lung cancer and a high titer of anti-Hu antibodies who developed a tonic left pupil and multiple cranial nerve palsies, including palsies of the left fifth through tenth nerves and both twelfth nerves, as in Garcin syndrome showing at least more than seven ipsilateral cranial nerve palsies, in the course of paraneoplastic sensory neuronopathy (PSN). Pathologic examination revealed no metastasis or direct invasion of malignancy with gliosis and perivascular inflammation throughout the brainstem, indicating paraneoplastic encephalomyelitis (PEM). The numbers of EBM11+ cells (probably reactive microglia), CD8+ cells, and CD4+ cells increased. Intracellular adhesion molecule-1 and lymphocyte function associated molecule-1 were expressed intensely on the endothelia of microvessels and were found to have infiltrated mononuclear cells around microvessels in the brainstem. Multiple cranial nerve palsies and their effects including the tonic pupil are likely due to the paraneoplastic effect of the primary systemic malignancy.