Two Cases of Thymic Carcinoma Initially Presenting as Bone Metastasis: A Clinical Report and the Usefulness of CD5 Immunohistochemistry for Assessing Bone Lesions.

Thymic carcinoma frequently spreads to the pleural space, regional lymph nodes, liver and lungs. However, an initial clinical presentation involving spinal or multiple bone metastases in patients with thymic carcinoma is extremely rare. We experienced two cases of thymic carcinoma that initially presented with spinal compression and severe pain due to multiple bone metastases, respectively. Both patients were histologically diagnosed with metastatic thymic squamous cell carcinoma based on the findings of specimens resected from the metastatic bone lesions. We herein describe the clinical courses of these cases and review the characteristics of bone metastasis of thymic carcinoma.