Discovery of the Primary Site of Esophageal Squamous Cell Carcinoma Based on Axillary Lymph Nodes Metastasis Detected with Fluorodeoxyglucose Positron-emission Tomography: Report of a Case

A 60-year-old Japanese man with no chief complaints underwent 18F-fluorodeoxyglucose positron-emission tomography (FDG-PET) during a medical check-up. FDG-PET revealed high tracer uptake in the left supraclavicular and axillary regions but no significant uptake in the esophageal region. However, upper gastrointestinal endoscopy revealed an ulcerative tumor in the middle third of the esophagus. Endoscopic biopsy revealed moderately differentiated squamous cell carcinoma. The patient underwent chemoradiotherapy. Follow-up FDG-PET and computed tomography after therapy revealed a complete response in the lymph nodes. The patient underwent subtotal esophagectomy with gastric tube reconstruction through the posterior mediastinum. However, metastasis to the axillary lymph nodes was detected 16 months after surgery, and lymph node dissection was performed. To our knowledge, this is the first reported case in which the primary site of esophageal squamous cell carcinoma was discovered on the basis of axillary lymph node metastasis detected with FDG-PET.