Lipomas occasionally can have other mesenchymal components, such as bone, cartilage, and vessels, and are classified as osteolipoma, chondrolipoma, and angiolipoma, respectively.1,2 Histologically, these are metaplasias from lipoma and not neoplastic changes.1,2 According to previous case reports, chondrolipomas and osteolipomas arise mostly from the breast5,6 or from the oral, nasopharyngeal, or pharyngeal regions.7–10 The occurrence in extremities is extremely rare: only five case reports of chondrolipoma are available.3,11–14
The gross appearance of the excised tumor consisted of a cartilaginous area with ossification in the lipomatous area (Figure 5). Histologically, the cartilaginous area contained mature chondrocytes and matrix, differing from chondroid lipoma.
Despite seeing central ossification in the cartilage component of the tumor, we could not establish whether the ossification developed from enchondral ossification in the cartilaginous area or from differentiation of lipomatous tissue. Cartilaginous tumors, such as synovial chondromatosis, enchondromas, soft-tissue chondromas, occasionally occur with ossification in chondroid matrix. On the other hand, they can arise from two different metaplasias such as ossification together with cartilage formation from lipoma. Recently, multipotent adult stem cells, the adipose-derived stem cells (ASCs), obtained from liposuction waste have the potential for chondrogenesis, osteogenesis, and myogenesis.18,19 Lipoma cells might have the potential to differentiate into other mesenchymal tissues. In our patient, the ossification area was focal and central surrounding the cartilage area. Moreover, the ossification pattern was similar to that in soft-tissue chondroma.20 Thus, we believe that ossification in chondrolipoma by enchondral ossification occurred over a long period of time. We finally diagnosed this from radiographs and pathological examinations as an ossifying chondrolipoma, not osteochondrolipoma.
In summary, we present a case of ossifying chondrolipoma of the thigh with radiographic and pathologic findings.
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