paraneoplastic neurological syndrome associated with occult small-cell lung carcinoma: tumor detection by FDG-pET

Abstract

Paraneoplastic neurological syndromes are rare disorders of the nervous system characterized by autoimmune attack due to cross reaction between antigens of the nervous tissue and onconeural antibodies. Their manifestation may precede the identification of an underlying neoplasm by months to years, as the malignancy sometimes remains latent even after repeated radiological assessment. we present a patient with mental and neuromuscular symptoms, as the presenting manifestation of a small-cell lung carcinoma (scLc) that was identified by FDG-PET. Case-report: A 63-year old man with a 12-month history of anxiety and depression was admitted to our department due to memory deficits and difficulty in ambulation. neurological examination demonstrated diffuse muscle wasting, fasciculations, absent tendon reflexes and a stocking-glove sensory deficit. csF examination showed lymphocytic pleocytosis, elevated protein and positive oligoclonal bands. Electrophysiological testing was compatible with axonal sensory neuropathy. needle electromyography of showed widespread fasciculation potentials. The combination of sensory neuropathy and motor neuron involvement raised the suspicion of a paraneoplastic syndrome. The patient underwent extensive serological testing for antibodies against onconeural antigens that revealed anti-hu positivity. A thorough investigation for latent neoplasia gave negative results. subsequent whole-body FDG-PET indicated active disease in subcarinal and right pulmonary hilar lymph nodes. open chest biopsy demonstrated scLc. The patient was put on chemotherapy with carboplatin/etoposid and local chest irradiation. he also received combined immuno-modulatory treatment with steroids and monthly intravenous immune globulin. Conclusion: Paraneoplastic disorders are a challenge. Early tumour identification is crucial for optimal patient management; however, even the most extensive screening for systemic cancer may prove unsuccessful. In cases with high clinical suspicion and positive anti-onconeural antibodies, PET scanning is indicated, when conventional imaging techniques fail to detect an underlying tumour.