Chondroid lipoma, a tumor of white fat cells. A brief report of two cases with ultrastructural analysis.

Chondroid lipoma is a recently described variant of lipoma with unusual morphologic features. Although classified as a fatty neoplasm, its phenotype is uncertain because it has not been determined whether cartilage is a real component or only simulated by light microscopy and whether the adipocytes demonstrate white or brown fat differentiation, issues that can be resolved only by electron microscopy. We present two cases of chondroid lipoma that ultrastructurally showed abundant intracytoplasmic lipid and glycogen and numerous pinocytotic vesicles, characteristic of white adipocytes. These findings support the conclusion that these tumors are composed solely of fat without true cartilage differentiation.