Chondroid lipomas are rare benign soft tissue tumours that, as you might guess, contain a varied ratio of both fat and cartilage. These lesions can be diagnostically confusing as they may mimic or be confused with other fat containing neoplasms, most importantly those of much greater clinical significance such as myxoid liposarcoma and extraskeletal myxoid chondrosarcoma 1.
Age at presentation may range from 14-70 years, with a 4:1 female predominance.
Histologic features that suggest chondroid lipoma include a fibrous capsule with nests and cords of uni and multivacuolated round cells within an extracellular myxohyaline matrix that has a cartilagenous appearance. These lesions may have rich vascularisation 2.
To arrive at a specific diagnosis of chondroid lipoma, immunohistochemical analysis may assist in distinguishing these lesions and myxoid liposarcoma or other more aggressive tumours 2.
An appendicular distribution predominates, with lesions most frequently encountered in the proximal extremities and limb girdles; however, cases have been reported in the trunk 6, head and neck as well 7.
These lesions may vary from predominately fat 4 to predominately chondroid tissue 3,6, with imaging features that match the relative distribution of constituent tissues. They also range from sub-centimeter to rather enormous. It is worth keeping in mind that imaging characteristics have not been extremely well-documented due to the rarity of this lesion and recent first description, in 1993.
Plain film and CT
Often seen as a mass like lesion of low density tissue (typically of fat attenuation) with or without internal calcification of the cartilaginous regions; however, fat may not be be a prominent feature and may not be readily identifiable 3,4,5.
Described features include a lobulated, encapsulated mass with areas that show typical fatty signal to a variable degree, with high signal on T1 and T2WI, suppressing with fat saturation. Cartilaginous portions of the lesion will show inhomogenously increased signal on fluid sensitive fat-suppressed images. Areas of calcification within the mass will appear hypointense on all pulse sequences 3,4,5,9.
Lesions may show heterogeneous and/or peripheral enhancement 9.
Lesions may be prominently 18F-FDG avid8.
Imaging differential considerations include:
- 1. Boets A, Van Mieghem IM, Sciot R et-al. Chondroid lipoma of the trunk: MRI appearance and pathologic correlation. Skeletal Radiol. 2004;33 (11): 666-9. doi:10.1007/s00256-004-0774-x - Pubmed citation
- 2. de Vreeze RS, van Coevorden F, Boerrigter L et-al. Delineation of chondroid lipoma: an immunohistochemical and molecular biological analysis. Sarcoma. 2011;2011: 638403. doi:10.1155/2011/638403 - Free text at pubmed - Pubmed citation
- 3. Logan P, Janzen D, O'Connell J et-al. Chondroid lipoma: MRI appearances with clinical and histologic correlation. Skeletal Radiology. 1996;25 (6): . doi:10.1007/s002560050143
- 4. Green RA, Cannon SR, Flanagan AM. Chondroid lipoma: correlation of imaging findings and histopathology of an unusual benign lesion. Skeletal Radiol. 2004;33 (11): 670-3. doi:10.1007/s00256-004-0818-2 - Pubmed citation
- 5. Hoch B, Hermann G, Klein MJ et-al. Ossifying chondroid lipoma. Skeletal Radiol. 2008;37 (5): 475-80. doi:10.1007/s00256-007-0444-x - Pubmed citation
- 6. Boets A, Van Mieghem IM, Sciot R et-al. Chondroid lipoma of the trunk: MRI appearance and pathologic correlation. Skeletal Radiol. 2004;33 (11): 666-9. doi:10.1007/s00256-004-0774-x - Pubmed citation
- 7. Murphey MD, Carroll JF, Flemming DJ et-al. From the archives of the AFIP: benign musculoskeletal lipomatous lesions. Radiographics. 2004;24 (5): 1433-66. Radiographics (full text) - doi:10.1148/rg.245045120 - Pubmed citation
- 8. Escobar E, Nguyen BD, Colvin OC. PET/CT and MRI of chondroid lipoma of the deltoid muscle. Clin Nucl Med. 2014;39 (11): 984-7. doi:10.1097/RLU.0000000000000543 - Pubmed citation
- 9. Setiawati R, Dimpudus FJ, Sun Z. Chondroid lipoma of the right thigh: Correlation of imaging findings and histopathology of an unusual benign lesion. Australas Med J. 2012;5 (7): 355-8. Free text at pubmed - Pubmed citation