Osteosarcoma of the patella: A case report

Abstract

We present a rare case of osteosarcoma involving the patella. A 30-year-old Japanese woman first consulted our out-patient clinic with a 2-year history of knee pain. Radiographs showed an enlargement of the patella with irregular distribution of both osteolytic and sclerotic lesions. Computed tomography and magnetic resonance imaging demonstrated soft tissue extension at the anterior part of the patella. Incisional biopsy showed abundant osteoid formation by spindle-shaped malignant cells, and the histological diagnosis was conventional osteosarcoma. The patient underwent preoperative chemotherapy, but there was no response. Furthermore, she developed a pathological fracture during chemotherapy. She underwent above-the-knee amputation with postoperative chemotherapy. She developed multiple metastases in the thoracic vertebrae 20 months after the surgery. At the most recent examination, she remains alive with multiple spinal metastases without paralysis 4 years after the surgery.

Primary tumors of the patella

“…OS mimicking GCT presented the multilocular lytic lesion [ 46 ]. Most of the cases had no cortical wall destruction in the patellofemoral joint [ 45 - 47 , 50 ]. The telangiectatic OS cases demonstrated a lytic lesion of the surrounding bone and osteoid matrix in the soft tissues extended from the patella [ 48 ].…”

“…The telangiectatic OS cases demonstrated a lytic lesion of the surrounding bone and osteoid matrix in the soft tissues extended from the patella [ 48 ]. CT scans could demonstrate soft tissue extension and an intraosseous lytic lesion with cortical thinning/breakthrough [ 46 , 47 ]. MRI was performed to determine the diagnosis as well as to detect changing of the adjacent soft tissues and bones [ 45 - 47 , 51 ].…”

“…CT scans could demonstrate soft tissue extension and an intraosseous lytic lesion with cortical thinning/breakthrough [ 46 , 47 ]. MRI was performed to determine the diagnosis as well as to detect changing of the adjacent soft tissues and bones [ 45 - 47 , 51 ]. The mass showed low signal intensity on T1-weighted images, and then T2-weighted images presented high signal intensity.…”

“…Surgery is still the main therapeutic approach. For patellar OS, surgical methods, including patellectomy (Enneking stage IIB, III) [ 45 , 50 ], wide resection (Enneking stage IIA) [ 46 ], amputation (Enneking stage IIB, III) [ 47 , 49 ], arthrodesis with an allograft and total joint replacement (Enneking stage III) [ 48 ], were performed in patellar OS cases. Before and after surgery, all of the patients experienced chemotherapy.…”

“…Before and after surgery, all of the patients experienced chemotherapy. The surgeon tried the above-knee amputation, due to the poor results of preoperative chemotherapy or previous surgery [ 47 , 49 ]. The excision was performed with safe surgical margins, including for patella, the quadriceps tendon, a patella tendon, intrapatellar fat pad, and a medial and lateral retinacula [ 45 , 46 ].…”