Two Cases of Lung Cancer-Associated Horner Syndrome With Divergent Outcomes Following Radiotherapy.

Horner syndrome is a well-recognized manifestation of sympathetic pathway disruption in lung cancer, particularly in apical lesions; however, its reversibility after treatment varies and remains difficult to predict. We report two cases of lung cancer-associated Horner syndrome that showed contrasting neurological outcomes following radiotherapy. In the first case, contrast-enhanced computed tomography (CT) demonstrated an apical lung tumor with a close anatomical relationship to adjacent neurovascular structures, and Horner syndrome failed to show sustained improvement after definitive radiotherapy. In the second case, contrast-enhanced CT revealed a supraclavicular lymph node metastasis without radiological evidence of direct neural invasion, and the neurological symptoms improved and remained stable after palliative radiotherapy. The differing post-treatment courses observed in these cases suggest that pre-treatment imaging findings, particularly the anatomical relationship between tumor lesions and surrounding neurovascular structures, may assist in prognostic estimation and patient counseling regarding the potential reversibility of Horner syndrome in patients with lung cancer.