Intrapatellar tendon lipoma with chondro-osseous differentiation: detection of HMGA2-LPP fusion gene transcript

A 54 year old man developed an unusual lipoma in the patellar tendon, consisting of a fibro‐adipose component and a chondro‐osseous component. The fibro‐adipose component contained mature adipocytes, lipoblasts, and fibroblasts; the chondro‐osseous component showed typical endochondral bone formation. Molecular analysis showed that the identical HMGA2‐LPP fusion transcript—characteristic of lipoma, parosteal lipoma, and pulmonary chondroid hamartoma—was detectable in the both components.