Osteomalacia. Serology for FGF23 was 1300 (normal < 180)
Cellular; spindle-stellate cells with patternless distribution
Pale eosinophilic cytoplasm with occasional clear vacuoles
Ovoid nuclei with angulation, hyperchromasia and minimal atypia; inconspicuous mitotic activity
Basophilic matrix with cystic degeneration
RNA-seq: negative
Hypocellular; spindle-stellate cells with patternless distribution
Pale eosinophilic cytoplasm
Ovoid nuclei with minimal atypia; inconspicuous mitotic activity
Basophilic matrix with areas of "grungy" calcification; occasional small vessels with thick hyalinized walls
RNA-seq: FN1::FGFR1 gene fusion
Hypocellular; sheets of polygonal cells, some of which are in lacunae-like spaces
Pale amphophilic cytoplasm
Ovoid nuclei with mild atypia; inconspicuous mitotic activity
Basophilic matrix with areas of "grungy" calcification; scattered osteoclast-type giant cells; cystic degeneration
IHC: ERG, SATB2
RNA-seq: FN1::FGFR1 gene fusion
Cellular; spindle-epithelioid cells with patternless distribution
Pale amphophilic cytoplasm with indistinct cell borders
Monomorphic ovoid nuclei; inconspicuous mitotic activity
Cystic degeneration with pools of proteinaceous fluid; prominent branching capillary vasculature
IHC: D2-40, ERG, SATB2
RNA-seq: negative