Isolated distal ulnar bone metastasis from lung squamous cell carcinoma: an extremely rare case report.

Bone metastases commonly occur in patients with lung cancer. However, metastasis from primary lung carcinoma to the bone below the knee and elbow is rarely encountered. We herein describe a man who developed an isolated distal ulnar bone metastasis originating from lung squamous cell carcinoma. A 68-year-old man presented to our orthopedic outpatient clinic for evaluation of a rapidly progressing tumor over his right wrist area. Tenderness with increased local temperature was noted, and the tumor was firm in consistency, oval-shaped, and 7 × 5 cm in size. Magnetic resonance imaging and radiographic imaging revealed an osteolytic tumor in his distal ulnar shaft. A 99m Tc-phosphate bone scan showed that this tumor was isolated and newly observed compared with the previous bone scan findings during initial diagnosis. Bone tumor biopsy confirmed metastatic squamous cell carcinoma. Segmental tumor resection with cementation was subsequently performed. This rare case report of an isolated ulnar metastasis includes detailed descriptions of the clinical, radiographic, and pathological features of the tumor.