A Rare but Sinister Cause of Shoulder Pain: A Case Report

Abstract BACKGROUND: Large cell neuroendocrine carcinoma (LCNEC) is a highly aggressive but rare cancer, especially when it first presents as shoulder pain. However, shoulder pain as a possible initial manifestation of lung cancer has been frequently reported. CASE PRESENTATION: An 84-year-old male, an ex-smoker, presented with left shoulder pain for two weeks. On examination, his clinical findings showed minor rotator cuff pathology and cervical spine degenerative changes. However, 6 months later, he was diagnosed of primary LCNEC lung cancer. CONCLUSION: The potential aetiologies of shoulder pain in a lung cancer case include: 1) Pain due to tumour invasion or supraclavicular lymph nodes compression of the brachial plexus; 2) Somatic referred pain due to stimulation of phrenic nerve or cervical structure; 3) Pain due to shoulder metastatic disease; 4) Radicular pain due to lower cervical nerve root impingement. Smoking and past cancer history should draw attention and lead to early investigations and regular follow-up reviews. Cautious interpretations of clinical examination and imaging findings are essential to increase diagnostic accuracy.