Abstract
RATIONALE: Lung cancer is a leading cause of cancer-related mortality and is often diagnosed late due to nonspecific or extrapulmonary symptoms. Atypical presentations in never-smokers with adenocarcinoma may delay diagnosis. This case highlights the diagnostic value of shoulder pain caused by unprovoked upper extremity deep vein thrombosis (UEDVT) as an early manifestation of thoracic malignancy. PATIENT CONCERNS: A 62-year-old male nonsmoker presented with a month-long history of progressive right shoulder pain radiating to the neck, without respiratory symptoms or trauma. The pain persisted despite analgesics. DIAGNOSES: Doppler ultrasonography showed acute thrombosis of the right subclavian, axillary, brachial, and internal jugular veins, explaining the shoulder pain. Contrast-enhanced computed tomography (CT) revealed a right hilar mass compressing vascular structures, and positron emission tomography-CT demonstrated mild hypermetabolism (maximum standardized uptake value = 3.1) without metastasis. Endobronchial biopsy confirmed epidermal growth factor receptor-mutant invasive adenocarcinoma. INTERVENTIONS: The patient was hospitalized for extensive UEDVT and treated with low-molecular-weight heparin, later switched to the direct oral anticoagulant. No thrombectomy or thrombolysis was required. A multidisciplinary tumor board planned surgical or chemoradiotherapeutic management based on resectability. OUTCOMES: Symptoms improved with anticoagulation, and the patient remained clinically stable pending oncologic therapy. LESSONS: Lung adenocarcinoma may rarely present with isolated shoulder pain as the initial symptom. When UEDVT is identified without an evident provoking factor, underlying malignancy should be thoroughly investigated. Additionally, epidermal growth factor receptor-mutant adenocarcinomas may demonstrate only mild fluorodeoxyglucose uptake on positron emission tomography-CT, emphasizing that low metabolic activity does not exclude cancer.