What are juxtacortical (near the cortex) manifestations?

From the Guidelines

Juxtacortical manifestations are characterized by their location adjacent to the cortex of a bone, and include variants such as parosteal and periosteal osteosarcomas, which are high-grade spindle cell tumors that produce osteoid or immature bone. These manifestations are significant in the context of osteosarcoma, a primary malignant bone tumor that is most common in children and young adults, with a median age at diagnosis of 20 years 1. The location of juxtacortical lesions is crucial in differentiating them from intramedullary lesions, and affects treatment approaches.

Key Characteristics of Juxtacortical Manifestations

• Located at the interface between the bone cortex and surrounding soft tissues
• Include various types of bone lesions such as juxtacortical (periosteal) chondroma, juxtacortical osteosarcoma, periosteal osteosarcoma, and parosteal osteosarcoma
• Characterized by their location at the bone surface rather than within the medullary cavity
• Appear attached to the outer surface of the bone cortex on imaging studies, sometimes causing cortical erosion or thickening

Diagnostic Implications

• The location of juxtacortical lesions helps differentiate them from intramedullary lesions
• Affects treatment approaches, with parosteal lesions tending to metastasize later than the classic form and having a low histologic grade 1
• The biological basis for these manifestations relates to the cellular origin of the lesion, often arising from periosteal cells or cells in the immediate vicinity of the cortex

Clinical Significance

• Juxtacortical manifestations are a critical aspect of osteosarcoma diagnosis and treatment, with implications for patient outcomes and survival rates. The identification of juxtacortical lesions is essential in the diagnosis and management of osteosarcoma, and their location and characteristics can inform treatment decisions and prognostic factors 1.

From the Research

Definition and Characteristics

• Juxtacortical osteosarcoma is a rare variant of osteosarcoma that arises from the cortical surface of the bone 2, 3.
• It is a highly malignant tumor, but has a better prognosis than conventional osteosarcoma, especially when treated early and aggressively 2, 3.
• Juxtacortical osteosarcoma can be classified into three distinct entities: parosteal, periosteal, and high-grade surface osteosarcoma 4.

Imaging and Diagnosis

• Surface lesions of bone, including juxtacortical osteosarcoma, can demonstrate distinct characteristics on imaging, which can present a diagnostic challenge 4, 5.
• Imaging features of juxtacortical osteosarcoma can include a marked degree of ossification without primary medullary involvement, and a tendency to grow from the periosteal tissues peripherally 3.
• Accurate imaging diagnosis is important, as surface sarcomas of bone can exhibit biologic features distinct from those of conventional intramedullary osteosarcoma 4.

Types and Classification

• Juxtacortical tumors of bone can be classified into five categories: cartilaginous, fibrous, lipomatous, osseous, and metastatic tumors 5.
• Juxtacortical osteosarcoma is a distinct malignant bone neoplasm, with a similar histological picture to conventional osteosarcoma, but with different clinical and X-ray findings 6.
• The prognosis of juxtacortical osteosarcoma depends on the degree of differentiation of the tumor, with well-differentiated tumors having a better prognosis than poorly differentiated ones 6.