An 83-year-old male ex-smoker presented to the Emergency Department with a 2-week history of progressive left-sided chest pain, associated with drooping of his left eyelid. The pain was not exertional or pleuritic in nature. Examination demonstrated left-sided partial ptosis and miosis, findings compatible with left-sided Horner syndrome(Figure 1A). The adjusted serum calcium concentration was 3.81mmol/l (normal range 2.2–2.6). Chest radiography showed a large left apical mass (Figure 1B). A presumptive diagnosis of Horner syndrome secondary to Pancoast’s syndrome was made. Horner syndrome can result from lesions anywhere in the oculosympathetic pathway, which includes thoracic lesions at the apex of the lung, as seen in this case. Figure 1. (A) Photograph demonstrating left-sided partial ptosis. Figure 1. (B) Chest radiograph showing a large left-sided apical lesion. Treatment was initiated for hypercalcaemia of malignancy with intravenous bisphosphonates and fluids. Computed tomography revealed an 8 centimetre mass in the left lung apex,invading the mediastinum to encase the left main pulmonary and subclavian arteries (Figure 1C), with posterior infiltration into the paraspinal muscles seen on magnetic resonance imaging (Figure 1D). Bilateral adrenal metastases were also seen.Ultrasound-guided biopsy yielded a Cytokeratin 7 positive adenocarcinoma, with KRAS mutation detected. Palliative radiotherapy was planned, but the patientdied 2 weeks after presentation. Figure 1. (C) Coronal view: Computed tomography of the chest demonstrating a large left apical lesion, with classical Pancoast tumour location. Figure 1. (D) Sagittal view: magnetic resonance imaging demonstrating invasion into the paraspinal muscles. 疾病名称：Pancoast's syndrome; Pancoast综合症; 肺尖肿瘤综合征; 潘科斯特氏综合征; 潘科斯特综合征 临床表现：Pancoast综合征由于一般记载概念较杂乱而含糊,不易导致清晰的诊断思路,而引起临床的一些漏诊与误诊。 完整的概念应是: Pancoast综合征为以癌侵及臂丛(主要是下干)为主的一组综合征,表现为 ①壁丛下干麻痹(Klumoke型瘫痪)即C8-T1脊神经前支麻痹,表现为以尺神经麻痹的一组症候群，该神经分布区感觉与运动障碍,以及该范围末梢的交感神经障碍-肢体水肿,紫绀、指甲营养障碍等,癌灶继续向内后方附近发展则可同时出现其它相应症状。 ②侵及星状神经节,则可出现同侧Homer征候群:瞳孔缩小(开大肌损伤),眼裂缩小(上睑扳肌损伤),眼球内陷(眶肌损伤),同侧面部潮红及无汗(面部皮肤血管和汗腺的交感神经和眼内肌交感神经同时受损)。 ③侵及喉返神经,则引起声音嘶哑。 ④侵及第一、二肋骨,则出现局部疼痛。 胸膜顶与上述诸结构间仅隔以一层薄的结缔组织——胸膜上筋膜( Sibson筋膜)，从臂丛下干至星状神经节及喉返神经间距仅约1cm。(见附图)由此解剖图不难分析出肺尖部癌所致 Pancoast综合征的原因来。 常见病因：有肺癌、胸膜间皮瘤、乳腺癌、甲状腺癌、食管癌等，以肺癌最多见，尤其是肺尖癌或肺上沟癌，有时为肺尖部转移性癌。