Marked improvement in opsoclonus and cerebellar ataxia after the surgical removal of a squamous cell carcinoma of the thymus: a case report.

A 69-year-old man with rapidly evolving vertigo and ataxia was admitted to our hospital. He was presented with a dysarthric speech and chaotic eye movements, identified as opsoclonus. Neurological examination revealed limb and truncal ataxias and an inability to stand unless fully assisted. A chest CT scan revealed a mass at the anterior mediastinum, which suggested paraneoplastic neurological syndrome (PNS). However, an extensive search for anti-neuronal antibodies linked to cerebellar ataxia failed to find any autoantibodies, including cell surface autoantibodies. Subsequently, a total surgical removal of the thymic tumor was performed, leading to marked improvements in his signs and symptoms. The pathological findings by conventional and immunohistochemical examinations confirmed a squamous cell carcinoma of the thymus. Three months after onset his signs and symptoms improved and he was able to walk without support. In contrast to thymomas, PNS is extremely rare in patients with thymic carcinoma. Previous reports have shown that neurological symptoms, similar to opsoclonus or cerebellar ataxia, deteriorated in cases of thymic carcinoma that could not be controlled. The present report indicates that early diagnosis and total removal of the rare neoplasm may increase the possibility of neurological recovery.