Anti-Hu paraneoplastic syndrome presenting with brainstem-cerebellar symptoms and Lambert–Eaton myasthenic syndrome

Paraneoplastic syndrome (PNS) with two distinct neurological features was reported in a 50-year-old man who presented initially with vertigo, ataxia, dysarthria, tremor, confusion, urinary retention and hypotension. Pulmonary X-ray findings, class IIIb sputum cytology, and positive anti-Hu antibody established the diagnosis of PNS associated with small-cell lung cancer (SCLC). Two cycles of combined chemotherapy resulted in shrinkage of the lung tumor together with complete recovery of neurological symptoms and disappearance of anti-Hu antibody. Relapse of SCLC 4 months later with re-appearance of anti-Hu antibody required additional chemotherapy and irradiation. Eight months later, when multiple liver metastasis of SCLC was noticed, muscular weakness with positive waxing phenomenon compatible with Lambert–Eaton myasthenic syndrome (LEMS) developed. Postmortem examinations revealed residual SCLC in the primary lung, and massive liver metastasis with generalized lymph node involvement, but no tumors in the CNS. In the cerebellum, there was a slight loss of Purkinje cells with torpedo formation but without apparent lymphocytic infiltration. The present PNS was unique in that the relapse of SCLC was accompanied by the appearance of anti-Hu antibody, and that initial signs of brainstem-cerebellar symptoms, encephalopathy and autonomic failure were replaced by LEMS coinciding with the tumor recurrence.