Review Question - QID 559

This case is an example of periosteal chondroma which is a rare benign surface lesion composed of cartilage. It can be similar in appearance and location to malignancies such as periosteal osteosarcoma or periosteal chondrosarcoma, so refining a differential diagnosis is important.

Figure A shows an eccentric, longitudinally oriented periosteal mass with an outer, sclerotic shell of reactive periosteum. Pressure from growth of the lesion may create a saucer shaped or complex shaped defect in the underlying bone. Periosteal chondromas can look similar to osteochondromas but they do not have a stalk or peduncle and myositis ossificans rarely involves the cortex like periosteal chondromas do.

Figures B and C show axial CT images illustrating the tumor extension from the underlying cortex.

Figure D shows a medium power histology of a periosteal chondroma displaying chondroid matrix with multiple chondrocytes in lacunae. Treatment of periosteal chondromas includes marginal excision including the underlying cortex.

The level 4 review by Lewis et al. presents a literature review and 10 cases of periosteal chondroma. They reported that all were treated by marginal or intralesional excision and there were no recurrences found.

Incorrect answers:
#1:Observation with serial radiographs is reserved for tumors such as osteochondroma or enchondroma.
#2: Irradiation treatment is not indicated for periosteal chondroma. Irradiation treatment is used more often as an option for Ewing sarcoma, primary lymphoma, or as an adjuvant to surgical excision of soft tissue sarcomas. Additionally it should be noted that the stated maximum dosage of 60 grays is relevant as irradiation beyond this would likely lead to soft tissue not healing.
#4:Wide surgical excision is reserved for malignancy such as chondrosarcoma, parosteal osteosarcoma, chordoma, and adamantinoma.
#5:Neoadjuvant chemotherapy, surgical excision, followed by adjuvant chemotherapy is appropriate treatment for intramedullary osteosarcoma, periosteal osteosarcoma, Ewing sarcoma, fibrosarcoma, rhabdomyosarcoma, and dedifferentiated chondrosarcoma.