Bone Tumors
Periosteal Osteosarcoma
GENERAL INFORMATION
Periosteal osteosarcoma is a distinct type of surface osteosarcoma (arises from the surface of the bone/periosteum)
It arises from the inner layer of the periosteum and therefore elevates the periosteum and produces a periosteal reaction
Periosteal osteosarcoma is primarily a chondroblastic tumor (composed mostly of cartilaginous tissue) that produces osteoid or bone
It has a predilection for the diaphysis of long bones particularly the tibia
Periosteal osteosarcomas are intermediate grade tumors as compared to conventional (most common type) osteosarcomas that are high grade. This means that periosteal osteosarcomas have less risk of metastasizing (spreading) and are associated with a better prognosis than conventional osteosarcomas. Periosteal osteosarcomas elevate the periosteum which causes a periosteal reaction to develop. They rarely invade the medullary canal of the bone. (This is different from a parosteal osteosarcoma which is a low grade, surface fibroblastic sarcoma that produces bone/osteoid, arises from the outer layer of the periosteum and therefore does not elevate the periosteum nor cause a periosteal reaction.)
Periosteal osteosarcomas constitute <2% of all osteosarcomas
CLINICAL PRESENTATION
Signs/Symptoms:
Limb swelling with or without pain for weeks to months before diagnosed
50% of patients are symptomatic for less than 6 months
95% of patients are symptomatic for less than 1 year
Sex Predilection: Male/Female 1:1.7
Age:
Most patients are 10-20 years of age; similar to conventional osteosarcoma; different from parosteal osteosarcoma that occurs primarily in patients from 20-40 years of age.
Sites:
Most commonly arises from the diaphysis of the tibia or femur (>85%); humerus, radius, ulna
RADIOLOGY
Plain X-Rays:
Diaphyseal lesion on external surface of bone; medullary canal uninvolved
Radiolucent mass extending into surrounding soft tissues
Saucerized cortex with chondroblastic soft tissue mass that is usually primarily radiolucent on plain X-rays
Periosteal reaction usually most evident feature on surface of bone (Hair on End or Sunburst appearance with spiculated pattern of calcification oriented perpendicular to the bone)
Cortical thickening at margins of erosion (40%)
Rarely may have Codman’s triangle
Spiculated or sunburst periosteal reaction (due to periosteal elevation)
Partial matrix mineralization may be seen consistent with
chondroblastic nature
Rare intramedullary invasion
MRI:
Mass on surface of bone
Intermediate signal on T1 weighted images and high signal on T2 consistent with cartilage
Usually no intramedullary invasion but may see slight erosion or saucerization of cortex
Periosteal reaction evident on MRI as very low signal on T1 and T2 weighted images
CT Scan:
Periosteal reaction evident and mass on surface of bone
May demonstrate subtle mineralization in tumor
X-Ray of Periosteal Osteosarcoma of Tibia
Periosteal Osteosarcoma of Tibia
X-Ray of Periosteal Osteosarcoma of Tibia
Surface tumor from tibia
Tumor is mostly cartilaginous with little mineralization and therefore is radiolucent
Hair on End Periosteal Reaction
Saucerization (minor erosion) of underlying cortex of bone
X-Ray of Periosteal Osteosarcoma of Tibia
MRI of Periosteal Ostesarcoma of Tibia
Tumor is on surface of bone
Mild saucerization of underlying cortex
Large mass
No intramedullary invasion
Primarily high signal on T2 weighted images consistent with cartilage
 
MRI: Axial T1 and T2 Weighted Images of Periosteal Osteosarcoma of Tibia
CT Scan of Periosteal Ostesarcoma of Tibia
X-Ray of Periosteal Osteosarcoma of Distal Femur
MRI: Periosteal Osteosarcoma of Distal Femur
MRI: T2 Weighted Axial Image of Periosteal Osteosarcoma of Distal Femur
CT Scan of Osteosarcoma of Distal Femur
PATHOLOGY
GROSS PATHOLOGY
Periosteal osteosarcomas are usually sharply defined
Attached to outer surface of cortex
May have areas of subtle cortical erosion
Cartilage usually visible and lobular
Invasion into nearby soft tissue/muscle
Bone spicules (periosteal reaction) extend from underlying cortex
Gross Specimen of Periosteal Osteosarcoma of Proximal Tibia
Gross Specimen of Periosteal Osteosarcoma of Proximal Tibia
Gross Specimen of Periosteal Osteosarcoma of Proximal Tibia
Gross Specimen of Periosteal Osteosarcoma of Proximal Tibia
MICROSCOPIC PATHOLOGY
Periosteal osteosarcomas demonstrate cartilage differentiation.
The cartilage appears intermediate to high grade.
There is prominent nuclear atypia
There may be poorly differentiated lobules of cartilage separated by malignant appearing spindle cells
Osteoid production by neoplastic cells is present
Osteoid is usually deposited in lace-like manner in between malignant spindle cells
Bone spicules have osteoblastic rimming and are reactive in nature (periosteal reaction)
Dense areas of calcification
Scant fibroblastic tissue may be present
Pathology: Primarily a Chondroblastic (Cartilaginous) Tumor with Bone (Osteoid) Production
Pathology of Periosteal Osteosarcoma
Differential Diagnosis of Periosteal Osteosarcoma
Periosteal Chondrosarcoma
Usually involves metaphysis
Ring and arc calcifications unlike periosteal osteosarcoma that is usually radiolucent and has radiating spicules of reactive bone (periosteal reaction)
Periosteal chondrosarcoma is usually without a periosteal reaction
Periosteal chondrosarcoma consists of low grade cartilage whereas periosteal osteosarcoma is higher grade with foci of malignant spindle cells and osteoid production
No osteoid production by a periosteal chondrosarcoma
Conventional Chondroblastic Osteosarcoma with Extraosseous
Extension
Differentiated radiographically from periosteal osteosarcoma
High Grade Surface Osteosarcoma
Highly pleomorphic and osteoblastic
Parosteal Osteosarcoma
Parosteal osteosarcomas are heavily mineralized metaphyseal lesions that are low grade fibroblastic tumors that produce osteoid or bone
BIOLOGICAL BEHAVIOR
Periosteal Osteosarcomas have a 15% metastatic rate
Most metastasize primarily to the lungs
TREATMENT/SURGERY
Treatment usually includes chemotherapy and surgery although the benefit of chemotherapy is controversial
Surgery:
Most tumors can usually be treated with a wide, limb sparing, en bloc resection and reconstruction
Rarely, very large or recurrent tumors may require amputation
Limb Sparing Surgery for a Periosteal Osteosarcoma of the Distal Femur
Exposure
Femur Cut and Tumor Removed
Defect After Removing Distal Femur
Modular Segmental Distal Femur Tumor Prosthesis for Reconstruction
Distal Femur Prosthesis Implanted
Distal Femur Tumor Prosthesis with Rotating Hinged Total Knee
Multiple Muscle Rotation Flaps for Closure and Reconstruction of Knee Extensor Mechanism
PROGNOSIS
15-25% metastatic rate to lungs
85-90% 5 year survival
Survival is much better than conventional osteosarcoma
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