Periosteal chondrosarcoma

JuxtaPeriosteal chondrosarcomas, previously also known as juxta-cortical chondrosarcomas, arecartilagineous or chondroid matrix-generating neoplasms originating in close association with the periosteum from conventional medullary chondrosarcomas and are therefore graded into low, intermediate or high-grade tumours (see chondrosarcoma grading)the bony surface ^1-3.

Terminology

The term ‘juxta-cortical chondrosarcoma’is no longer recommended ¹.

Epidemiology

Typically it occursPeriosteal chondrosarcomas are rare and make up for about ~2-2.5% of all chondrosarcomas ^1,2. They occur in adultsa wide age range with a peak in theirthe 3^rd decade and a male gender preference ^1-4.

Diagnosis

The diagnosis of periosteal chondrosarcoma is slightly more frequentmade by a combination of clinical information, location and origin of the tumour as well as the invasion of the bony cortex or tumour size and can be eventually confirmed by histology ^1-4.

Diagnostic criteria

Diagnostic criteria according to the WHO classification of soft tissue and bone tumours (5th edition)¹:

• cartilaginous tumour originating from the surface of the bone in malesclose association with the periosteum

• tumour invasion of the underlying osseous cortex or tumour size >5 cm

Clinical presentation

Clinically periosteal chondrosarcomas can present with swelling and/or pain and sometimes even motion restriction due to the swelling or neurological symptoms ^1,2.

Pathology

Unlike conventional chondrosarcomas, theyperiosteal chondrosarcomas arise from the surface of the bone in close association with the periosteum, lifting the periosteum over themselves as. The underlying cortex is usually thickened and cortical invasion is seen in the majority of cases ³.

Aetiology

The aetiology of periosteal chondrosarcoma is unknown ¹.

Location

They typically arise from long bones, with a fibrous pseudocapsulepredilection for the posterior aspect of the distal femur.

Radiographic features

The underlying cortex is usually thickened or may be eroded, however, extension into the medullary cavity is not usual.

Where the periosteum is lifted a Codman triangle may be seen. In addition to the usual chondroid matrix, metaplastic ossification is also common.

Differential diagnosis

• periosteal osteosarcoma

  • affects younger patients (typically 10-25 years of age)

  • periosteal reaction perpendicular to the cortex

  • diaphyseal rather than metaphyseal

• parosteal osteosarcoma

  • stalk of bony attachment

  • otherwise similar appearance, location and demographics

• juxtacortical chondroma

• parosteal lipoma