Sirs: Paraneoplastic brainstem encephalitis (BE) is often part of an encephalomyeloneuritis, but may also occur as an isolated clinical entity [4]. It is mostly associated with small cell lung cancer (SCLC), yet some patients develop BE in the course of other tumours. We describe a case of BE associated with a malignant fibrous histiocytoma (MFH) and an atypical anti-neuronal antibody. A 74-year-old man presented with a 2 months history of myoclonus involving the upper extremities. Neurological examination confirmed myoclonus and revealed increased tendon reflexes on the right. Blood studies were normal except for a mildly increased serum level of alfa-fetoprotein. Brain MRI demonstrated only mild cerebral and cerebellar atrophy. The patient was treated with clonazepam with improvement of the myoclonus. The search for antineuronal antibodies in the serum revealed the presence of an atypical antibody, raising the hypothesis of a paraneoplastic neurological disorder (PND). Abdominal CT disclosed a retroperitoneal mass and multiple hepatic and lymphatic formations. Biopsy of a lateral aortic lymph node showed a MFH. At this time, the patient’s neurological state had markedly deteriorated, with dysarthria, truncal and appendicular ataxia, right pyramidal syndrome, left hypoglossal palsy, skew deviation, convergence nystagmus and diplopia with paresis of the right oculomotor nerve. Brain MRI was unchanged. Cerebrospinal fluid (CSF) examination showed mild increase in albumin, normal cell count and intrathecal Ig synthesis with IgG index of 0.77 (normal upper limit for our laboratory < 0.70) and some oligoclonal bands exclusively in the CSF. Testing for anti-neuronal antibodies showed a 1:2000 titre in the serum, consistent with the diagnosis of paraneoplastic BE, and a 1:10 titre in the CSF. The patient underwent surgical removal of the retroperitoneal mass followed by successful chemoand radio-therapy, with oncological remission and neurological improvement. Six months later, no neurological abnormality was present. One year after the diagnosis, he presented again with dysarthria and gait ataxia. CT revealed a retroperitoneal tumour recurrence and an enlarged hepatic metastasis. The patient underwent surgery for excision of the retroperitoneal mass and died from post-operative complications after one week. Serial samples of serum and CSF, obtained during the course of the disease, were examined for the presence of anti-neuronal antibodies. The immunohistochemical analysis using sections of rat’s cerebellum demonstrated an atypical reactivity directed towards axons in the granular and basal molecular layer and around the Purkinje cells (Fig. 1). The reactivity persisted in the serum with unchanged titre after tumour removal. Immunoblot against recombinant Hu-D, Yo and Ri was negative. Western-blot analysis usLETTER TO THE EDITORS