Pathology: non-ossifying fibroma

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