Sheets of epithelioid-polygonal cells
Amphophilic cytoplasm
Ovoid nuclei with small nucleoli; mitotic activity
Scant collagenous stroma; sheets of foamy histiocytes; scattered osteoclast-like multinucleated giant cells
IHC: keratin (AE1/AE3), SATB2
RNA-seq: negative
Sheets of spindle-polygonal cells a vague storiform pattern
Pale cytoplasm and indistinct cell borders
Monomorphic ovoid nuclei; inconspicuous mitotic activity
Interspersed osteoclast-like multinucleated giant cells, foamy histiocytes. and lymphocytes
IHC: CD34
RNA-seq: HMGA2::NCOR2 gene fusion
PMID: 33742141