Tumors and tumor like lesions of the patella - Pictorial essay

Abstract

Focal lesions of patella are not infrequent. The patella is an uncommon location for neoplasms. The majority of tumors of the patella are benign, with a significant incidence of chondroblastoma and giant cell tumor. Other lesions include aneurysmal bone cysts, osteoid osteoma and osteoblastoma. In our experience chondroblastoma is the most common benign tumor. Malignant tumors include osteosarcoma, lymphosarcoma and metastasis. Radiological features are similar to the lesions at other sites except periosteal reaction is uncommon. However, tumor like lesions often pose a difficult problem in ruling out a real neoplasm which is important in order to avoid a biopsy. These include developmental, traumatic, infective, metabolic and endocrinal entities. Miscellaneous lesions include Paget disease and degenerative joint disease. Radiologically, it is important to identify the tumor like lesions and to differentiate them from primary neoplasms. Advanced imaging is rarely necessary, but histological confirmation is mandatory.