Chondromyxoid fibroma

Tumor biology and incidence

  • Rare benign, aggressive cartilage tumor characterized by lobulated areas of spindle shaped and myxoid (stellate) cells, with abundant chondroid or myxoid matrix and interspersed giant cells
  • Not known to metastasize.
  • Least common cartilage tumor, 1% of all primary bone tumors
    • Accounts for 2% of benign bone tumors

Age

Most common from 10-30 years of age; mainly adolescents and young adults

Gender

Male:Female = 2:1

Presentation

  • Pain near a joint without a history of trauma
  • Occasionally tender wwelling
  • Pathologic fracture (rare)
  • May present with a soft tissue mass and restriction of motion
  • Constitutional symptoms usually absent

Physical findings

  • Swelling
  • Tenderness to palpation of the affected area
  • Decreased range of motion

Plain films

  • Eccentric, radiolucent lesions with well-defined margins
  • Sclerotic border and "soap bubble" appearance common
  • Usually a purely lytic lesion, but can have mineralization and calcification
  • No periosteal reaction
Site
  • Metaphysis of long, tubular bones
  • More often found in the lower extremity: proximal tibia,  distal femur
  • Usually central in location if in the small bones of the hand
Size

Between 1 and 10 cm, with 3-4 cm the average

Tumor effect on bone
  • Radioluscent
  • Can cause fusiform expansion in small bones
Bone response to tumor
  • Sharply circumscribed, geographic, with a sclerotic, scalloped margin
    • Metaphyseal reactive sclerosis frequently observed, producing the geographic margin
  • Eccentric lobulated bony expansion/periosteal neo-corticalization may occur
  • Pseudocapsule appearance
Matrix

Calcifications not often seen on plain radiographs

Cortex

Often eroded or ballooned out

Soft tissue mass

None

Bone scan

  • Increased uptake of chondromyxoid fibromas seen on bone scan, but contributes little to diagnosis
  • Multiple lesions highly uncharacteristic of chondromyxoid fibroma

CT scan

  • Helps define architecture and cortical integrity
  • Can show mineralization of tumor

MRI

Typical cartilaginous lesions: Demonstrate low signal intensity on T1-weighted images and high signal intensity on T2-weighted images

Differential diagnosis

  • Giant cell tumor (generally older patients, do not have calcifications; borders generally less well defined)
  • Chondrosarcoma
  • Fibrous dysplasia and non-ossifying fibroma
  • Chondroblastoma (epiphyseal; rarely metaphyseal)
  • Unicameral bone cyst (rare after teens; lesion is central)
  • Aneurysmal bone cyst (also eccentric, but has greater cortical expansion)
  • Infection
  • Osteoblastoma
  • Osteosarcoma (either telangiectatic or chondroblastic)
  • Brown tumor

Natural history

  • No metastatic cases reported
  • Can be locally aggressive
  • Can cause bone destruction
  • Propensity to recur once treated
  • If untreated, tends to grow and infiltrate surrounding tissues

Pathology

  • Gross: firm tan tissue
  • Microscopic: Lobular pattern
    • Lobule is less cellular centrally
    • Composed of stellate cells in a myxoid or chondroid type matrix
    • At periphery, more cellular, with spindle shaped cells
    • Multinucleated cells also present

Diagnosis and treatment

  • Open biopsy usually necessary for this rare tumor
  • Curettage and bone grafting or marginal excision
  • Consider en bloc resection with a marginal margin if location permits removal without significant associated morbidity
  • Recurrence rates lower than 20%

Complications

  • Local recurrence rates reported between 15-25%, depending on age of the patient and type of resection (higher with intralesional excision)
  • Pathologic fracture through the lesion occurs 5% of the time
  • Complications related to surgical treatment
    • Infection
    • Failure of allograft
    • Fracture
  • Malignant transformation rare; reported in association with radiation treatment
    • XRT contraindicated

Recommended reading

Nielsen GP, Keel SB, Dickersin GR, Selig MK, Bhan AK, Rosenberg AE.Chondromyxoid fibroma: a tumor showing myofibroblastic, myochondroblastic, and chondrocytic differentiation. Mod Pathol. 1999 May;12(5):514-7.


Wu CT, Inwards CY, O’Laughlin S, Rock MG, Beabout JW, Unni KK. Chondromyxoid fibroma of bone: a clinicopathologic review of 278 cases. Hum Pathol. 1998 May;29(5):438-46.


Yamaguchi T, Dorfman HD.Radiographic and histologic patterns of calcification in chondromyxoid fibroma. Skeletal Radiol. 1998 Oct;27(10):559-64.