Periosteal chondrosarcoma

Last revised by Joachim Feger on 13 Jan 2024

Periosteal chondrosarcomas, previously also known as juxta-cortical chondrosarcomas, are cartilagineous or chondroid matrix-generating neoplasms originating in close association with the periosteum from the bony surface 1-3.

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

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

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

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

  • cartilaginous tumor originating from the surface of the bone in close association with the periosteum

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

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

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

The etiology of periosteal chondrosarcoma is unknown 1.

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

Unlike conventional chondrosarcomas, periosteal chondrosarcomas arise from the surface of the bone in close association with the periosteum, lifting the periosteum over themselves. The underlying cortex is usually thickened and is seen in the majority of cases 3,4.

The etiology of periosteal chondrosarcoma is unknown 1.

The most common sites involved are the metaphyses of tubular long bones especially the distal femur and the proximal humerus 1-3.

Grossly, periosteal chondrosarcomas are characterized by the following features 1,3:

  • lobulated mass on the bony surface sometimes extending into the soft tissues

  • often large tumors >5 cm, rarely they can be small <3 cm

  • grayish-glistening cut surface with gritty-white spots of calcification

  • erosion of the bony cortex

Histomorphologically, periosteal chondrosarcomas display the following microscopical features 1,3,4:

  • lobular moderately cellular cartilaginous tumor with myxoid matrix

  • similarity to conventional central chondrosarcoma

  • no direct bone or osteoid formation

  • neocortex formation or metaplastic bone formation at the periphery in almost half of the cases

  • commonly invasion of the underlying bony cortex

  • intramedullary extension can be seen

  • clear delineation from the soft tissues

Immunohistochemistry stains are negative for CDK4 or MDM2 1.

IDH1 and IDH2 mutations which can be found in conventional central chondrosarcoma are expressed in a subset of cases. EXT1 is expressed normally without mutations that are found in secondary peripheral chondrosarcomas 1,3. There might be dysregulations of RB1 signaling pathways. Unlike in parosteal osteosarcoma CDK4 or MDM2 amplification is absent 1,3.

General radiographic signs of periosteal chondrosarcomas include the following 1-4, 6-8:

  • lobulated morphology

  • altered underlying bony cortex (can be thinned or thickened) 1,5

  • often large tumors (>5 cm)

  • periosteal shell (metaplastic ossification)

Radiographic features of periosteal chondrosarcomas include the following 1-3,,6-8:

They appear as a lobulated cartilaginous mass with a chondroid or myxoid matrix, lifting the periosteum from the cortex. Cortical invasion or destruction is often present. Intraosseous/intramedullary extension might not always be appreciated on MRI 5-8, but if present favors an intermediate to high-grade over a low-grade tumor 9,10. Soft tissue extension might be present 6,7.

  • T1: low to intermediate signal vs muscle

  • T2/STIR: high signal intensity with punctate or curvilinear signal voids indicating matrix mineralization

  • T1 C+ (Gd): peripheral and septal enhancement

Rarely tumors are <3 cm then they are difficult to diagnose on imaging 5 and special attention should be paid to cortical destruction and/or intramedullary invasion even though the latter is not always apparent on MRI 5.

PET-CT shows increased uptake of FDG 8.

The radiological report should include a description of the following 5-10:

  • tumor size and location (metaphysis, diaphysis)

  • tumor margins/surface

  • intralesional calcifications

  • cortical erosion/destruction

  • association to the periosteum/periosteal shell

  • extension into the medullary cavity

  • soft tissue extension

Surgical excision is recommended 1. Most recommend wide/en-bloc excision, whereas others conclude that marginal excision is adequate  2-4. Clinical and morphological parameters do not predict the outcome of those tumors 1,4.

Complications include local recurrences and distant metastases mainly to the lungs in up to 12% 1,4.

Periosteal chondrosarcoma was first described by the American bone pathologist Louis Liechtenstein in 1955 11.

The main differential diagnoses of low-grade peripheral chondrosarcomas are 1,5,12:

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Cases and figures

  • Case 1: T2
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  • Case 2a: metatarsal
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  • Case 2b: metatarsal
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