Pathology: ossifying fibromyxoid tumour

Ossifying fibromyxoid tumour

  • Circumscribed; epithelioid-spindle cells arranged in fascicles, nests and cords

  • Pale eosinophilic cytoplasm

  • Round-ovoid nuclei with small nucleoli and mild atypia; occasional mitotic activity

  • Incomplete rim of metaplastic bone; hyalinized collagen arranged in bands, and "starburst" patterns

  • IHC: S100

  • RNA-seq: failed (presumably due to decalcification)

Ossifying fibromyxoid tumour

  • Circumscribed; epithelioid-spindle cells with fascicular and reticular patterns

  • Pale eosinophilic-amphophilic cytoplasm; in areas the cells contain one or two large clear vacuoles

  • Round-ovoid nuclei with small nucleoli and mild atypia; inconspicuous mitotic activity

  • Myxoid stroma with microcytic degeneration; hyalinized collagen with "starburst" pattern

  • Ossification is not present

  • RNA-seq: PHF1::TFE3 gene fusion

  • PMID: 30920708

Ossifying fibromyxoid tumour

  • Epithelioid-spindle cells with vague fascicular pattern

  • Pale amphophilic cytoplasm

  • Round-ovoid nuclei with small nucleoli and mild atypia; inconspicuous mitotic activity

  • Myxoid stroma with delicate collagen fibres

  • Ossification is not present

  • RNA-seq: PHF1::FOXR2 gene fusion

Ossifying fibromyxoid tumour

  • Spindle cells with vague fascicular pattern

  • Pale amphophilic cytoplasm with long tapering processes

  • Ovoid-elongated nuclei with small nucleoli and mild atypia; inconspicuous mitotic activity

  • Myxoid stroma with delicate collagen fibres

  • Ossification is not present

  • RNA-seq: CREBBP::BCORL1 gene fusion

  • PMID: 27537276

Ossifying fibromyxoid tumour, malignant

  • Epithelioid-spindle cells arranged in fascicles, nests and cords

  • Pale amphophilic cytoplasm

  • Round-ovoid nuclei with small nucleoli and mild atypia; conspicuous mitotic activity

  • Necrosis; bands of hyalinized collagen

  • Ossification is not present

  • IHC: S100

  • RNA-seq: HCFC1::PHF1 gene fusion*

* To date unreported

Ossifying fibromyxoid tumour, malignant

  • Epithelioid-spindle cells arranged in fascicles, nests and cords

  • Pale amphophilic cytoplasm

  • Round-ovoid nuclei with small nucleoli and mild atypia; conspicuous mitotic activity

  • Necrosis; broad bands of hyalinized collagen

  • Ossification is not present

  • IHC: S100, SATB2

  • RNA-seq: ZC3H7B::BCOR gene fusion

  • PMID: 24285434

Ossifying fibromyxoid tumour, malignant

  • Spindle-epithelioid cells arranged in vague fascicles

  • Pale amphophilic cytoplasm with delicate tapering processes

  • Hyperchromatic ovoid nuclei with mild atypia; mitotic activity

  • Ossification present on imaging

  • IHC: S100

  • RNA-seq: CREBBP::BCORL1 gene fusion

  • PMID: 27537276