Presentation
Forearm pain and swelling.
Patient Data
The intramedullary tumor involved nearly the full length of the ulna, with the exception of the proximal olecranon. The surrounding cortex also is involved, and the soft-tissue components at the dorsal and ulnar sides appeared hyperintense due to edema.
Case Discussion
Microscopic appearance is related to malignant round cell tumor.
Tumor necrosis and sheet-like distribution of the neoplastic cells is seen.
The cells have scant cytoplasm, coarse nuclear chromatin and high nuclear to cytoplasmic ratio.
The neoplastic cells also show a strong and diffusive membranous CD99 reactivity.