Sinonasal Osteosarcoma

Michelle A. Michel, MD

Key Facts

Terminology

Rare malignant bone tumor arising from primitive bone-forming mesenchyma

Imaging

> 50% of craniofacial OSa arise in jaw
- Mandible > maxilla
- < 50% involve extragnathic bones (skull, orbit, sphenoid & ethmoid bones, or zygoma)
CT best for delineating osteoid matrix & cortical involvement
- Hyperdense mass with osteoid matrix & periosteal reaction
MR optimal for evaluating extent within marrow & adjacent structures

Top Differential Diagnoses

Chondrosarcoma
Ossifying fibroma
Osteoma
Fibrous dysplasia
Metastasis

Pathology

Up to 25% are secondary malignancy in prior radiation field
Increased incidence in hereditary retinoblastoma
May arise in bone affected by Paget disease, fibrous dysplasia, multiple exostoses, enchondromatosis

Clinical Issues

Most present in 3rd-4th decades
Older than classical OSa of long bones
No strong gender predilection
Craniofacial OSa accounts for 6-13% of all OSa
Surgical resection is mainstay of treatment
- Neoadjuvant chemotherapy has significantly improved cure rates

(Left) Coronal bone CT shows an aggressive mass involving the maxilla with soft tissue filling the maxillary antrum and nasal cavity. There is extension into the orbit

and infratemporal fossa

. Note the “sunburst” periosteal reaction

consistent with osteosarcoma. (Right) Axial T1WI C+ FS MR shows an avidly enhancing left maxillary osteosarcoma filling the antrum and extending into the nasal cavity