Author(s)

Reiko Yamaguchi¹, Seiichi Matsumoto¹, Keisuke Ae¹, Taisuke Tanizawa¹, Tabu Gokita¹, Keiko Hayakawa¹, Yuki Funauchi¹, Munehisa Kito¹, Hirotada Ishii², Noriko Motoi³

¹Department of Orthopaedic Surgery, Cancer Institute Hospital, Tokyo, Japan.
²Ishii Orthopaedic Clinic, Tokyo, Japan.
³Division of Pathology, Cancer Institute Hospital, Tokyo, Japan.

Osteosarcomas are primary malignant tumors that are characterized by the production of osteoid or immature bone. However they are the most common primary malignant tumor of bone in adolescents and young adults, the diagnosis of osteosarcoma is often delayed. It is because of the rarity of population, the variety of findings, nonspecific symptoms and so on. A 46-year-old male patient had left knee pain for 3 months without any symptoms in his right knee. At a nearby clinic, X-ray of his healthy side was taken by chance. The irregular bone formation was however seen in the metaphysis of the distal femur with spreading into the soft tissues. No abnormal findings were pointed out at his left side knee. A diagnosis of pleomorphic sarcoma was made by incisional biopsy. Pulmonary CT showed multiple nodules which were considered as multiple lung metastases. He was diagnosed as right femoral sarcoma, clinical stage IV (T1N0M1a) by TNM classification. He underwent preoperative chemotherapy, followed by limb-saving operation. No preoperative complaints were found in his left knee. Final diagnosis of surgically resected specimen was osteoblastic osteosarcoma which showed neoplastic osteoid formation within pleomorphic malignant cells. However, osteosarcomas occurred in adult populations are sometimes occurred as a secondary neoplasms, he had a history of diabetes but no other medical history, such as radiation therapy for a solid cancer, Paget’s disease, other benign bone lesions or inherited conditions. As far as our knowledge, we believe that this is a first case report of asymptomatic incidental osteosarcoma.

Incidental Osteosarcoma, Asymptomatic Osteosarcoma, De Novo Osteosarcoma

Yamaguchi, R. , Matsumoto, S. , Ae, K. , Tanizawa, T. , Gokita, T. , Hayakawa, K. , Funauchi, Y. , Kito, M. , Ishii, H. and Motoi, N. (2015) Case Report: Asymptomatic Osteosarcoma. Case Reports in Clinical Medicine, 4, 369-375. doi: 10.4236/crcm.2015.412075.