Paraneoplastic neurological syndrome as an initial indicator of small cell carcinoma of the lung.

Paraneoplastic syndromes are indirect manifestations of cancer due to functional peptides/hormones produced by a tumour, or due to cross reactivity between tumour and host antigens. Here the case of a 58-year-old woman presenting with ataxia, paraesthesia and subacute and progressive loss of vision is reported. The patient exhibited strong serum positivity for anti-Hu and anti-CV2 antibodies, and a chest CT scan showed a hypodense nodule in proximity of the right upper lobe bronchus and an enlarged ipsilateral paratracheal lymph node that was not visible on a lung x-ray. Histopathological examination of a biopsy specimen from this lymph node showed that small cell carcinoma of the lung was present. The patient's deficits were subsequently diagnosed as three coexisting paraneoplastic neurological syndromes (PNSs): subacute cerebellar ataxia, sensory neuropathy and retinopathy, respectively. Although rare, PNSs can be the first manifestations of cancer, and their rapid recognition facilitates an early treatment.