Radiological Case: Osteoblastic Osteosarcoma

Kevin Cronin, MS; Marilyn Bui, MD, PhD; Jamie T. Caracciolo, MD, MBA


Appl Radiol. 2015;44(7) 

In This Article

Case Summary

A 43-year-old woman from Puerto Rico presented to a local medical facility with a 2-year history of a left-sided distal forearm mass. The patient denied any history of pain, trauma or constitutional symptoms. Forearm radiographs (Figure 1A) and subsequent contrast-enhanced MRI were performed in Puerto Rico, which raised concern for a bone tumor. An open biopsy was obtained. Histopathology demonstrated irregular lamellar bone with hypocellular fibrous stroma, but no obvious atypia, mitotic activity or necrosis mimicking fibrous dysplasia (Figure 3A). Thus, a benign fibro-osseous lesion was diagnosed and follow-up was recommended. Three months later, follow-up radiographs demonstrated changes consistent with a more aggressive neoplasm. At this point, the patient presented to our institution reporting recent growth and new intermittent dull, burning pain exacerbated by maximal supination. On examination, a firm, nontender mass was appreciated on the dorso-medial aspect of the distal ulna with terminal supination defect compared with the contralateral forearm. Three-view radiographs of the wrist (Figure 1B), high-resolution MRI (Figure 2), and secondary review of outside pathology slides (Figure 3B) were performed.

Figure 1.

(A) AP radiograph demonstrates a sclerotic lesion of the distal ulna including an associated extra-osseous component with smooth, continuous margination; no complex or irregular periosteal reaction. (B) AP radiograph six months later demonstrates increased soft tissue mass with spiculated "hair-on-end" periosteal reaction (*) and new periosteal disruption (arrow).

Figure 2.

(A, B) Coronal T1-w and fat-suppressed T2-w and axial T1-w and (C, D) contrast-enhanced MR imaging demonstrates a moderately T2-w hyperintense and avidly enhancing soft tissue mass arising from the distal ulna with extra-osseous extension of disease.

Figure 3.

(A) H&E stain X100. Pre-treatment biopsy demonstrates bland spindle cell proliferation and irregular bony trabeculae resembling fibrous dysplasia. (B) H&E stain X200. Pre-treatment biopsy at higher power demonstrates malignant cells with round and spindle nuclei infiltrating irregular bony trebeculae with evidence of osteoid formation.