Epiphyseal chondroblastoma of bone

Pain in the anterior knee has become synonymous with patella chondromalacia. However, pain also is the first sign of a tumor of the patella. Tumors of the patella are rare, but they often are mistaken for other benign lesions. Benign tumors of the patella are more frequent than malignant tumors (73% versus 27%). The most common benign neoplasms are giant cell tumor and chondroblastoma. Margin of the lesion, cortical involvement, trabecular pattern, and type of the matrix are important features for a radiographic diagnosis. Bone scans, computed tomography scans, and magnetic resonance images are used for staging of the tumor before surgery. Curettage only should be considered for patients with Stage 1 or Stage 2 benign lesions. Patellectomy is indicated for patients with Stage 3 aggressive benign tumors and for patients with Stage IA malignant tumors. A patellectomy with excision of involved soft tissues is used in patients with Stage IB tumors, whereas in patients with Stage IIA tumors, an extensive patellectomy is indicated. In patients with Stage IIB tumors, an extraarticular resection of the knee is preferred when there is a small soft tissue involvement, but amputation is necessary when there is a large soft tissue mass.