Isolated abducens nerve palsy secondary to lung metastases

We present a rare case of metastatic lung adenocarcinoma which presented as isolated abducens nerve palsy. A 65-year-old healthy woman presented with horizontal diplopia of three months duration. Her best-corrected visual acuity was 6/18 bilaterally with no relative afferent pupillary defect. Ocular examination showed limited abduction of the right eye. Anterior and posterior segment examination was normal in both eyes. However, she had a non-tender enlarged lymph node at the left supraclavicular area. The systemic review was unremarkable.C-reactive protein, erythrocyte sedimentation rate, and serum alpha-fetoprotein were markedly raised. A chest X-ray revealed right upper lobe opacity with a satellite nodule. Computed tomography of the brain, orbit, thorax, abdomen, and pelvis exhibited a heterogeneously enhancing mass at the right upper lobe of the lungwith metastasis to the left frontal, right occipital, and left parietal lobe as well as multiple bone metastases. With histopathology confirmation of lung tissue biopsy, she was diagnosed as isolated right abducens nerve palsy secondary to metastatic lung adenocarcinoma. She was referred to the respiratory, neuromedical, andoncology units for further management. In conclusion, although this appeared to be an isolated case, lung metastasis should be considered in the differential diagnosis of isolated abducens nerve palsy. Hence, lung examination should be performed when encountering such cases.