Periosteal chondrosarcoma of the rib: a case report

Abstract

Periosteal chondrosarcomas, also known as juxtacortical chondrosarcomas, are a rare subtype of chondrosarcoma. They usually present with pain and swelling over the affected site, most often arising in the appendicular skeleton, with the metaphysis of the distal femur and humerus the most common sites. In this poster we present the case report of a periosteal chondrosarcoma arising on the internal surface of the right 8th rib, making this an unusual site for such a tumour. Periosteal chondrosarcomas differ macroscopically from the differential diagnosis of chondroma in both size, as periosteal chondrosarcomas are often greater than 5cm, and by showing invasion into the adjacent bone or surrounding soft tissue. Histologically they have a lobulated appearance with chondrocytes showing atypia and binucleation. They can be differentiated from osteosarcoma in that no malignant osteoid or bone formation can be seen. This case report presents a rare tumour at an unusual site and discusses the differential diagnoses to be considered when making a diagnosis of periosteal chondrosarcoma.