Anti-hu neuropathy as a paraneoplastic syndrome: the pursuit for the primary site.

Abstract

A 53-year-old man with a history of smoking and recent weight loss presented with progressive weakness and difficulty walking. Physical exam evidenced dysmetria on finger-to-nose test, worsened with eyes closed, pseudoathetosis, absent deep tendon reflexes and a neuropathic pattern of hypoesthesia and hypopalesthesia. He was unable to stand due to the severity of the ataxia. Initial investigation was positive for syphilis, with no history of treatment, and cerebrospinal fluid analysis showed hyperproteinrachia with normal cell count. Despite adequate treatment with penicillin, symptoms continued to progress. Electroneuromyography was remarkable for axonal sensorimotor polyneuropathy with sensitive predominance. A paraneoplastic panel was ordered and evidenced positivity to anti-Hu. The patient was then treated with high doses of methylprednisolone and plasmapheresis, with no improvement. An extensive search for malignancies was performed, and enlarged hilar lymph nodes were found on computed tomography scan. Positron Emission Tomography-scan showed pulmonary and mediastinal hypermetabolism. Tissue samples were acquired with no significant findings and tuberculosis, fungal infections and inflammatory granulomatous diseases, among other conditions, were ruled out. Due to the high suspicion for malignancy, the biopsies were reviewed by a pulmonary pathology specialist, submitted to additional immunohistochemical staining and, at last, the diagnosis of small cell lung carcinoma was made. Chemotherapy was initiated shortly after.