Location: Epiphysis or apophysis of long bones (proximal femur and humerus), flat, and short bones.

Clinical: Modest pain.

Imaging: On x-ray, like a chondroblastoma. Osteolytic lesion with small calcifications, sharp margins, irregular, and ill-defined sclerotic rim. On CT, spots or small granules typical of the cartilaginous tumors.

Histopathology: Lobular tissue with clear cells: central nucleus, extremely vacuolated cytoplasm, strongly PAS positive. Rare mitotic figures. Peripheral reactive giant cells, possible areas of well-differentiated chondrosarcoma, and intercellular calcification like chondroblastoma, cystic spaces, and reactive osteoid.

Course and staging: Slow growth, recurrence is possible when intralesional margins are obtained, metastases are exceptional. Usually, stage IA.

Treatment: Wide resection. Prognosis is good.