Chondrosarcoma

Chondrosarcoma is a malignant bone tumor in which neoplastic cells produce chondroid (cartilaginous) matrix without osteoid bone formation. It is the second most common primary bone malignancy in adults after osteosarcoma. Subtypes include conventional (intramedullary, central) chondrosarcoma graded 1–3 by cellularity, atypia, and mitotic activity (75–85% of cases); peripheral chondrosarcoma arising from osteochondroma (multiple osteochondromas, Ollier, Maffucci); dedifferentiated chondrosarcoma (juxtaposition of low-grade cartilage and high-grade non-cartilaginous sarcoma, dismal prognosis); mesenchymal chondrosarcoma (younger patients, small round cell areas); clear cell chondrosarcoma (low-grade, epiphyseal); and periosteal chondrosarcoma.

Anatomic distribution: pelvis (most common, especially periacetabular and ilium), proximal femur, proximal humerus, ribs and sternum, and scapula. Patients typically present aged 40–70 years (median 50–60), with younger age in mesenchymal subtype. Clinical features include deep dull aching pain unrelieved by rest and progressive over months, palpable mass (especially in superficial bones), pathologic fracture, and rarely systemic symptoms.

Imaging: radiograph and CT show intramedullary lytic lesion with chondroid mineralization (rings and arcs, popcorn), cortical destruction, endosteal scalloping >2/3 cortex thickness, and soft tissue mass. MRI delineates intramedullary extent, soft tissue component, and joint involvement. Histology requires expert pathology to grade and exclude enchondroma. Treatment: wide en bloc surgical resection with negative margins is mainstay (limb-salvage with reconstruction when possible). Conventional chondrosarcoma is generally radio- and chemo-resistant. Adjuvant radiotherapy reserved for positive margins or unresectable lesions; chemotherapy used in mesenchymal (Ewing-like protocols) and dedifferentiated subtypes. Five-year survival: grade 1 80–90%, grade 2 50–70%, grade 3 20–40%, dedifferentiated <10%.