Bone Tumors
Telangiectatic Osteosarcoma

Telangiectatic osteosarcoma is a variant of an intramedullary high grade osteosarcoma.
Accounts for 3% of osteosarcomas
Telangiectatic osteosarcoma is extremely lytic on X-rays. It demonstrates very little osteoid production.
It is characterized by cystic spaces filled with blood that are separated by thin septa.
It is a cancerous tumor largely composed of cystic cavities containing necrosis and hemorrhage
It  is postulated that telangiectatic osteosarcomas grow so rapidly that they outgrow there blood supply. Hence portions of the tumor die (undergo necrosis) and form cystic cavities that fill with hemorrhage.
The cystic spaces filled with hemorrhagic material leads to the presence of fluid-fluid levels on MRIs (so called ABC-like changes or telangiectatic change)
ABC- like changes can sometimes lead to a misdiagnosis on X-rays and the tumor may be misinterpreted as being a benign ABC.

Signs/Symptoms:
Similar to Conventional Osteosarcoma
Dull pain and swelling for a few months duration are common presenting symptoms
Night pain
Alkaline phosphatase levels are usually normal
Pathologic fractures occur in 25% of patients because the lesion is extremely lytic.

Sex: Male to female 2:1

Age: Affects most patients in the second decade of life (teenagers)

Sites: 50% of cases located in knee area
Distal femur, proximal humerus, proximal tibia
Most arise from the metaphysis (90%); diaphyseal (10%)

X-ray:
Permeative lesion with indistinct border that is poorly marginated
Osteolytic and expansile on X-ray with very little osteoid production
Osteoid usually not discernible on X-ray but scant and faint lace-like osteoid may be detectable on a CT scan
No surrounding sclerosis
May have Codman's triangle and malignant appearing periosteal reaction in most cases
Cortical destruction and soft tissue extension are common
Pathologic fracture (25%-30%)
Expands contour of bone and may appear similar to an ABC (aneurysmal bone cyst)

MRI/CT:
Fluid-fluid levels secondary to cystic cavities filled with blood products. The sediment from blood products settle to the gravity dependent area of the cavity and the fluid component floats to top thus forming a fluid-fluid level.

MRI and CT are also useful for demonstrating the local extent of the tumor and any soft tissue mass

CT also useful for demonstrating scant osteoid production

Bone scan: Donut sign

X-Ray:  Telangiectatic Osteosarcoma of Proximal Tibia

Lytic lesion with indistinct (permeative) margin
Metaphyseal origin
Codman's triangle
Cortical destruction
No ossification detected on plain x-ray

Xray:  Telangiectatic Osteosarcoma of Proximal Tibia

CT Scan:  Telangiectatic Osteosarcoma of Proximal Tibia

MRI:  Telangiectatic Osteosarcoma of Proximal Tibia Multiple Fluid-Fluid Levels are Demonstrated

X-Ray:  Telangiectatic Osteosarcoma of Distal Femur

MRI:  Telangiectatic Osteosarcoma of Distal Femur Multiple Fluid-Fluid Levels

X-Ray:  Telangiectatic Osteosarcoma of Proximal Humerus

Permeative, lytic tumor with indistinct moth-eaten border
Cortical destruction
Expansile lesion with soft tissue mass
No ossification on X-ray

X-Ray:  Telangiectatic Osteosarcoma of Proximal Humerus

X-Ray:  Telangiectatic Osteosarcoma of Distal Radius

MRI:  Demonstrating Multiple Fluid-Fluid Levels

MRI:  Telangiectatic Osteosarcoma of Distal Femur Multiple Fluid-Fluid Levels are Demonstrated

Telangiectatic osteosarcomas have a variable gross appearance
They may appear as a large blood clot filling a single large cystic cavity; hemorrhagic and necrotic mass; or a multicystic fluid-filled lesion
Thin septae exist between the cystic cavities that harbor malignant appearing spindle cells producing scant osteoid
Fleshy and sclerotic tissue typical of a conventional osteosarcoma is not seen
Its gross appearance can mimic an aneurysmal bone cyst
Mixture of large cystic and spongy areas

Gross Specimen:  Telangiectatic Osteosarcoma of Proximal Tibia

Tumor has cyst-like spaces divided by septa
~Septa composed of atypical, bizarre, malignant appearing spindle cells with atypical nuclei and atypical mitotic figures
~Osteoid production is scant, focal and lace-like

High degree of nuclear atypia, cellular pleomorphism, normal and atypical mitotic activity

In highly necrotic tumors that appear grossly as blood clot, malignant cells may be separated in a background of necrotic and bloody debris and may be difficult to identify.

Low power architecture demonstrates multiple blood filled cystic cavities separated by multiple septae

High power view of septa; malignant appearing cells with large, hyperchromatic atypical nuclei, scant osteoid

High power view of septa showing malignant spindle cells in cavity wall, cystic cavities are filled with blood

Conventional osteosarcoma with dilated vascular spaces

Aneurysmal Bone Cyst (ABC)
~ABC usually has more sharply defined margins
~ABC usually has peripheral “egg shell” calcification indicating that the periosteum is intact around the soft tissue component (a benign radiographic feature)
~ABC may have osteoid production in wall but the osteoid is usually surrounded by benign appearing osteoblasts with plump cytoplasm and uniform features; the osteoid is typically laid down in a sheet or trabecular appearance
~Telangiectatic osteosarcoma has bizarre, atypical malignant cells and scant, lace-like osteoid

Aneurysmal Bone Cyst

Microscopic Pathology ABC

Fast growing, rapidly dividing, high grade tumor with high risk for metastases (spreading)
With tumor progression
Massive bone destruction
Formation of large palpable soft tissue mass
Often invasive growth of surrounding soft tissue with cortical erosion
Metastases (similar to conventional osteosarcoma):
Lungs are most common sites of metastases
Bones are second most common site

Preoperative (induction) chemotherapy (typical regimens utilize these medications; treatment usually follows same regimen as conventional osteosarcoma; most patients are treated according to Children’s Oncology Group Protocols):
Adriamycin (doxorubicin)
Cisplatinum (cisplatin)
High Dose Methotrexate (HDMTX)
Ifosfamide/Etoposide in some regimens
(usually 2 or 3 cycles and then surgery)

Surgery:
Wide surgical resection/limb salvage
Amputation for large unresectable tumors and other rare instances

Postoperative (adjuvant) chemotherapy:
Same regimen as preop; usually 4 cycles but can vary

Surgical principles are the same as those employed for conventional osteosarcoma

Nowadays, most patients can be treated with a limb sparing resection instead of an amputation

Prosthetic replacements, cadaver allografts, vascularized bone grafts as well as other methods have been used to reconstruct extremities after tumors are removed

Proximal Tibia Tumor Resected

Defect after Resection of the Proximal Tibia

 

Reconstruction with a Modular Proximal Tibia Tumor Prosthesis

 

Reconstruction with a Modular Proximal Tibia Tumor Prosthesis

 

Rotational Gastrocnemius Muscle Flap to Cover and Protect Prosthesis with Good Healthy Muscle Tissue and Reconstruct the Extensor Mechanism of the Knee