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Table 3 Differential diagnostic features

From: Chondromyxoid fibroma-like osteosarcoma: a case series and literature review

Age (years)All agesAll ages, preferably < 3030–40>  4010–14 and > 40
SiteCraniofacial part; femurProximal tibia, distal femur; iliumDistal femur, proximal tibiaBones of the pelvis; proximal femur, proximal humerus, distal femur; ribDistal femur, proximal tibia, proximal humerus
Location in the long boneVariableMetaphysis; eccentric in long bonesMetaphysis, diametaphysisMetaphysis or Diaphysis; Centric in long bonesMetaphysis
CRpoorly defined osteolytic, osteogenic or expansive lesionWell-defined osteolytic lesionLarge, lytic coarsely trabeculated lesion with a focal aggressive featureOsteolytic lesion with endosteal scalloping; cortical thickeningLarge, poorly defined, mixed lytic and blastic mass
CTCortex destructionSclerotic marginCortex destruction; periosteal reactionMineralization; cortex erosion or destructionMineralization, ossification; cortex destruction; periosteal reaction
MRISoft tissue mass; Soft tissue and bone marrow oedemaPeripheral nodular enhancement; no bone marrow or soft tissue oedemaSoft tissue extension; difficult to distinguish from COSRing-and-arc enhancement; soft tissue oedemaSoft tissue mass; soft tissue and bone marrow oedema
HistologyLoose aggregates of cells supported in a highly myxoid stroma; Neoplastic boneLobular pattern with stellate or spindle-shaped cells in a myxoid backgroundHypocellular to moderately cellular fibroblastic proliferation with variable amounts of osteoid production; neoplastic boneAbundant blue-grey cartilage matrix production; atypical chondrocyte varying in size and shape with enlarged, hyperchromatic nucleiNeoplastic cells with severe anaplasia and pleomorphism; neoplastic bone
ImmunohistochemistryVimentin (+); S100 (−)S100 (+); collagen II, SOX9 (+) in the centre of lobulesMDM2, CDK4 (+)20% IDH1(+) with IDH R132H antibodyosteocalcin, osteonectin, S100, action, SMA, NSE, CD99 (+); Factor VIII, CD31, CD45 (−)
GeneticNoneChromosome 6 aberrationGain or amplification of MDM2 (12q13–15)IDH1 mutationMultiple numerical and structural chromosomal aberrations
  1. CMF-OS Chondromyxoid fibroma-like osteosarcoma, CMF Chondromyxoid fibroma, LGCO Low-grade central osteosarcoma, CHS Chondrosarcoma, COS Conventional osteosarcoma