Pulmonary adenocarcinoma associated with SAPHO syndrome difficult to differentiate from multiple bone metastasis

The patient was a 57-year-old man with a chief complaint of anterior chest pain who was diagnosed with clinical stage IV (c-T2N2M1) non-small-cell lung cancer (adenocarcinoma). Tenderness in the sternoclavicular joint, acne, periodontitis, and palmoplantar pustulosis were evident, and SAPHO syndrome was diagnosed. SAPHO syndrome is a rare disorder that results in synovitis, acne, pustulosis, hyperostosis, and osteomyelitis. Bone scintigraphy showed tracer accumulation in the costal cartilage, sternoclavicular joint, and cervical vertebrae 6-7. Although the bone lesions of SAPHO syndrome were difficult to differentiate from bone metastasis of pulmonary adenocarcinoma, metastatic bone tumors were ruled out by magnetic resonance imaging, computed tomography, and fluorodeoxyglucose positron emission tomography. There have been no previously reported cases of lung cancer with comorbid SAPHO syndrome. We report such a case and discuss the relevant literature, particularly that concerned with the evaluation of bone lesions.