Osteochondromyxoma
Osteochondromyxomas (OMX) are very rare benign tumors with both a chondroid and osteoid matrix mostly seen within the Carney complex.
Epidemiology
Generally, osteochondromyxomas are extremely rare. Within the Carney complex, they occur in about 1% of the patients and are usually seen early in life often even before 2 years. In adults, they can appear as a separate entity .
Associations
Osteochondromyxomas are a rare criterion and associated with other features of the carney complex .
Clinical presentation
The typical complaint is a painless mass. It might be also found within a skeletal survey for the carney complex.
Pathology
Osteochondromyxomas are tumors with a chondroid and osteoid matrix and extensive myxoid changes .
Location
The tumor has been found in the following locations :
- facial bones and skull including the sellar region
- diaphyseal areas of long bones (tibia and radius)
- chest wall/ribs
- spine
Macroscopic appearance
Macroscopically osteochondromyxoma usually appears as a well-circumscribed, gelatinous, cartilaginous, light-yellowish, hemorrhagic tumor usually without capsule that can show cortical erosion .
Microscopic appearance
Microscopic features of osteochondromyxomas include the following :
- variable cellularity in an abundant myxoid, cartilage-like and partly osteoid matrix
- chondroblast-like and osteoblast-like cells
- occasional mitoses
Immunohistochemistry
Immunohistochemistry stains might be occasionally positive for S100 .
Genetics
Osteochondromyxoma is associated with inactivating mutations in the tumor suppressor gene PRKAR1A on chromosome 17q22-24 within the Carney complex .
Radiographic features
General imaging features of osteochondromyxoma are heterogeneous and vary with the location . A ring-like or bubbly appearance has been described for radiographs and cross-sectional imaging :
- lytic or mixed sclerotic and lytic lesion
- expansile or permeative growth
Plain radiograph
On plain radiographs desmoplastic fibroma of bone will usually show the following characteristics :
- osteolytic or mixed osteolytic/mildly sclerotic matrix
- well-defined or partly well-defined margins
- possible endosteal scalloping
CT
CT might show a soft tissue density with calcifications and/or osteoid matrix and sometimes cortical erosions.
MRI
In addition to the general imaging features MRI displays the following :
Signal characteristics are usually as follows:
- T1: heterogeneous, mixed-signal intensity (isointense or hypointense to muscle)
- T2: heterogeneous, predominantly, high signal intensity
- T1 C+ (Gd): heterogeneous enhancement
Radiology report
The radiological report should include a description of the following:
- form and location
- tumor margins and transition zone
- cortical breakthrough
- endosteal scalloping
Treatment and prognosis
The tumor can be managed surgically and complete excision is curative, however, with incomplete resection, local recurrence is quite common .
History and etymology
The Carney complex was first described by J. Aidan Carney in 1985 .
Differential diagnosis
Conditions which can mimic the presentation and/or the appearance of desmoplastic fibroma of bone include :
