Spindle cells with storiform pattern
Pale eosinophilic cytoplasm
Monomorphic ovoid nuclei; inconspicuous mitotic activity
Interspersed osteoclast-type multinucleated giant cells; interstitial haemorrhage with siderophages; occasional woven bone trabeculae
IHC: (-) H3.3 G34W
Spindle cells with storiform pattern
Amphophilic cytoplasm
Monomorphic ovoid nuclei; inconspicuous mitotic activity
Interspersed osteoclast-type multinucleated giant cells; occasional foamy histiocytes; reactive bone