summary Telangiectatic Osteosarcomas are rare, malignant, high-grade osteosarcomas that occur most commonly in the proximal humerus, the femur, and proximal tibia. Patients typically present between the ages of 5 and 25 with regional pain and swelling. Diagnosis is made with biopsy showing high-grade sarcoma with mitotic figures is seen in intervening cellular areas and lakes of blood mixed with malignant cells. Treatment is usually neo-adjuvant chemotherapy, limb salvage surgical resection, followed by adjuvant chemotherapy. Epidemiology Incidence rare (4% of osteosarcomas) Demographics male > female Anatomic location proximal humerus, proximal femur, distal femur, proximal tibia occur in same location as ABC Risk factors history of prior radiation Etiology Genetics associated with the following mutations tumor suppressor genes Rb-1 p53 oncogenes HER2/neu c-myc c-fos Presentation Symptoms pain similar in ABC in presentation (must differentiate) 25% present with pathologic fracture Physical exam soft tissue swelling local tenderness Imaging Radiographs lytic, destructive, and expansile lesion; entire cortex may be compromised Bone scan shows increased uptake MRI indications indicated in all cases to determine soft tissue involvement findings fluid-fluid levels extensive edema in surrounding tissue Studies Histology characterized by high grade sarcoma with mitotic figures is seen in intervening cellular areas lakes of blood mixed with malignant cells (not in ABC) not as much osteoid as intramedullary osteosarcoma histology is critical to differentiate from ABC Gross pathology will show "bag of blood" Differential ABC diagnosis needs to be confirmed by an experienced musculoskeletal pathologist differentiating ABC from telangietic osteosarcoma is difficult and critical both have similar radiographic appearance both have large blood filled spaces both have similar location (proximal humerus, proximal femur, distal femur, proximal tibia) ABC vs Telangiectatic Osteosarcoma Aneurysmal Bone Cyst Telangiectatic Osteosarcoma Epidemiology 75% of patient < 20 years. Locations (proximal humerus, proximal femur, distal femur, proximal tibia) Locations (proximal humerus, proximal femur, distal femur, proximal tibia) Radiographs Expansive, eccentric and lytic lesion with bony septae Expansive, eccentric and lytic lesion with bony septae MRI Clear fluid levels May extend into soft tissue. Fluid levels less defined Edema in surrounding tissue Histology Blood-filled spaces, spindle cells, benign giant cells, no evidence of malignant cells Lakes of blood mixed with malignant cells with mitotic bodies Treatment Operative neoadjuvant chemotherapy, limb salvage resection, followed by adjuvant chemotherapy indications standard of care in most patients surgical resection trend towards limb salvage whenever possible can be performed in close to 90% of cases chemotherapy preoperative chemotherapy given for 8-12 weeks followed by maintenance chemotherapy for 6-12 months after surgical resection doxorubicin/cisplatin/methotrexate/ifosamide 98% necrosis with chemo is good prognostic sign expression of multi-drug resistance (MDR) gene portends very poor prognosis cells can pump chemo out of cell present in 25% of primary lesions and 50% of metastatic lesions outcomes risk of recurrence is decreased with good cellular response/wide surgical margins Complications Local recurrence uncommon (~5%) associated with poor prognosis increased risk of recurrence in patients with displaced, pathologic fracture Prognosis Prognostic variables poor advanced tumor stage is most important indicator increased lactate dehydrogenase (LDH) and alkaline phosphatase (ALP) expression of multi-drug resistance (MDR) gene pathologic fractures increased risk of recurrence favorable 98% necrosis with chemo is good prognostic sign Survival more chemosensitive but same survival as intramedullary osteosarcoma 5 year survival with tumor localized to an extremity is ~70% 5 year survival with metastases is ~20%