Chondroid lipoma is a rare, benign, lipomatous soft tissue tumour that manifests as a painless lump. Tumours are located most frequently in the proximal extremity and limb girdle, then in decreasing frequency in the leg, trunk, head and neck region, foot, and hand.4
Tumour depth was predominantly in the deep subcutis or skeletal muscle. The median tumour size was 4cm, and usually occurs predominantly in middle-aged adults. Women are more commonly affected than men. An accurate diagnosis is essential in guiding the treatment plan; however, imaging and histologic examination are not always conclusive, and reliance may be placed on immunohistochemical features.1
There are few reports of imaging studies of chondroid lipoma. Reports of chondroid lipoma with evidence of radiographic calcification are very limited.7
In this case, a large tumour was found in the right thigh with presence of calcification, as shown in the radiographic images. The curvilinear calcification within the soft tissue mass raised a differential diagnosis of an extraskeletal chondroma or chondrosarcoma, a lipomatous lesion together with fat necrosis, or even synovial sarcoma.
MRI features of chondroid lipoma help to make the diagnosis, although MRI appearances of6 chondriod lipoma were only reported in a very few studies. 1
MRI images demonstrate the typical fatty components based on signal intensity. Chondroid lipoma reflects the large fat and chondroid consistency of the tumour. These lesions often reveal high signal of fat peripherally, but contain nodular foci representing cartilage matrix of low signal intensity relative to muscle on T1 and T2 weighted MRI images. High signal intensity indicative of fat observed on T1- or T2-weighted MRI images is suppressed on Fat - supressed or short time-to-inverse inversion-recovery weighted (STIR) images, as is noticed in this case. These MRI findings are similar to the previous cases of chondroid lipoma with intralesional calcification. 6
At gross pathological examination, chondroid lipoma is an encapsulated, often multilobular, yellow to white mass with a size range of 1–11 cm. Chondroid lipomas are characterised by the presence of cells resembling chondroblasts and lipoblast mature adipose tissue, and myxoid matrix. These features may closely resemble myxoid liposarcoma or extraskeletal myxoid chondrosarcoma and thus lead to a pseudosarcomatous misdiagnosis. Immunohistochemically, tumour cells are consistently positive for vimentine and S100 protein. Positivity for CD68 and cytokeratins also has been observed.2
Unlike other malignant tumours such as chondrosarcoma which require the consideration of radical surgery and postoperative radiotherapy, chondroid lipoma is considered to be treated successfully with local excision. No recurrences, metastasis, or lead to malignant transformation have been observed. 6
In conclusion, we report a case of chondroid lipoma of the right thigh, a rare benign adipose tissue tumour containing mature fat and chondroid matrix. The correlation between radiological features as well as clinical presentation and the cytohistomorphology of this case plays an important role in making accurate diagnosis and guiding the treatment plan. In particular, we demonstrate the typical MRI appearances of chondroid lipoma, in addition to the calcification within the tumour shown on radiographic images. A combination of MR imaging and radiography is needed to make the clinical diagnosis of chondroid lipoma.