|Classification and external resources|
A chondromyxoid fibroma (CMF) is an extremely rare benign cartilaginous neoplasm which accounts for < 1% bone tumours.
The majority of cases occur in the second and third decades, with approximately 75% of cases occurring before the age of 30 years 1,12-15. There is no recognised gender predilection. Examples have however been seen in patients up to the age of 75 years. In some series there is a male predilection 12 whilst in others no such distribution is found 2
Typically patients present with progressive pain, often long standing and/or bony swelling and restricted range of movement in affected limb 3,12. The latter is most often the case in bones with little overlying soft tissues (e.g. short tubular bones of the hands and feet).
Most chondromyxoid fibromas are located in the metaphyseal region of long bones (60%), and may extend to the epiphyseal line and even rarely abut the articular surface 3,12. They are almost never just epiphyseal 3. The classical site is the upper 1/3rd of tibia ( which accounts for 25% of all cases) with the small tubular bones of the foot, the distal femur and pelvis being other relatively common locations 12.
Rarely occur in the skull or skull base.
The tumour comprises a variable combination on chondroid, myxoid, and fibrous tissue components organised in a pseudolobulated architecture 20.
On gross examination they are typically seen as solid glistening tan-gray intraosseous masses.
Occasional osteoclast-like giant multinucleated cells are encountered particularly at the periphery. Most cells are morphologically bland, and mitotic figures are rare or absent 13.
Plain film often seen as a lobulated, eccentric radiolucent lesion long axis parallel to long axis of long bone no periosteal reaction (unless a complicating fracture present) geographic bone destruction: almost 100% well defined sclerotic margin: 86% there can be presence of septations (pseudotrabeculation): 57% 2 there can be presence of matrix calcification in a small proportion of cases: 12.5%1 MRI MR features are often not particularly specific. Signal characteristics include
T1 - low signal T1 C+ (Gd) - the majority (~70%) tend to show peripheral nodular enhancement ~ 30% diffuse contrast enhancement and this can be either homogeneous or heterogeneous 19 T2 - high signal Bone scan A scintigraphic "doughnut sign" has been described in this tumour type 11. However, this is very non-specific and can be found in a plethora of other bone lesions.
Treatment and prognosis
They are benign lesions and malignant degeneration is rare. They are usually treated with curettage which however have a high recurrence rate of 25%. As such if an en-bloc resection is possible this is advisable
- Hakan T, Vardar Aker F (July 2008). "Chondromyxoid fibroma of frontal bone: a case report and review of the literature". Turk Neurosurg 18 (3): 249–53. PMID 18814113.
- Nord KH, Lilljebjörn H, Vezzi F et al. (2014). "GRM1 is upregulated through gene fusion and promoter swapping in chondromyxoid fibroma". Nat Genet 46 (5): 474. doi:10.1038/ng.2927. PMID 24658000.
- Armah HB, McGough RL, Goodman MA et al. (2007). "Chondromyxoid fibroma of rib with a novel chromosomal translocation: a report of four additional cases at unusual sites". Diagn Pathol 2: 44. doi:10.1186/1746-1596-2-44. PMC 2203974. PMID 18036245.
- Thompson AL, Bharatha A, Aviv RI, Nedzelski J, Chen J, Bilbao JM, Wong J, Saad R, Symons SP. Chondromyoid fibroma of the mastoid facial nerve canal mimicking a facial nerve schwannoma. Laryngoscope. 2009 July; 119(7):1380-1383. Epub 2009 June 8.