Chondroid Lipoma : Differential Diagnosis

Comments:
Differential Diagnosis of Chondroid Lipoma: The differential diagnosis includes malignant tumors like extraskeletal myxoid chondrosarcoma, myxoid liposarcoma and chordoma; and benign entities such as soft tissue chondroma, myoepithelial tumors and spindle cell lipomas.

Myxoid liposarcomas: Closely resemble chondroid lipomas due to myxoid matrix, bland ovoid or round cells, and lipoblasts. Chondroid lipomas are well-circumscribed, show transition to lipomatous areas, and lack the plexiform capillary network of myxoid liposarcomas. Chondroid lipomas also lack the t(12;16)(q13;p11) or the less common t(12;22)(q13;q11-12) translocations that fuse DDIT3 with FUS or EWSR1 genes.

Extraskeletal Myxoid Chondrosarcomas: Seen in 4th-6th decades of life, male predilection, deep infiltrative mass in proximal limb and limb girdles; cords of anastomosing polygonal cells with eosinophilic cytoplasm in myxoid matrix; no fatty component or cytoplasmic vacuoles; carry recurrent translocations that fuse NR4A3 on 9q22 to a variety of gene partners such as EWSR1 on 22q12.

Chordoma occurs in axial locations and is positive for keratins and brachyury.

The image shows chondroid lipoma with close resemblance to the tumors mentioned above. Note the presence of lipoblasts and mature adipocytes.