Pathology: plexiform fibrohistiocytic tumour

Plexiform fibrohistiocytic tumour, histiocytoid-type

  • Multinodular

  • Clusters of histiocytes with abundant eosinophilic cytoplasm; monomorphic round-ovoid nuclei with prominent nucleoli and inconspicuous mitotic activity

  • Interspersed osteoclast-type giant cells frequently surrounded by small pools of erythrocytes

  • Siderophages and haemosiderin deposition

  • Desmoplastic background; vascular invasion


Plexiform fibrohistiocytic tumour, fibroblast-type

  • Multinodular

  • Clusters of spindle cells with fascicular pattern; eosinophilic cytoplasm; ovoid nuclei with mild atypia and inconspicuous mitotic activity

  • Interspersed osteoclast-type giant cells

  • Myxoid-collagenous stroma; focal metaplastic bone