Pathology: spindle cell / sclerosing rhabdomyosarcoma

Rhabdomyosarcoma, spindle cell

  • Spindle-epithelioid cells in fascicles

  • Abundant eosinophilic cytoplasm

  • Round-ovoid nuclei with prominent nucleoli and moderate pleomorphism; conspicuous mitotic activity

  • Interspersed rhabdomyoblasts

  • IHC: desmin, myogenin, keratin (AE1/AE3)

Rhabdomyosarcoma, spindle cell

  • Spindle-epithelioid cells in fascicles

  • Abundant eosinophilic cytoplasm

  • Round-ovoid nuclei with prominent nucleoli and moderate pleomorphism; conspicuous mitotic activity

  • IHC: desmin, myogenin, keratin (AE1/AE3)

  • RNA-seq: FUS::TFCP2 gene fusion

  • PMID: 29431183, 36374445

Rhabdomyosarcoma, spindle cell

  • Spindle cell fascicles with variable cellularity

  • Abundant eosinophilic cytoplasm with bipolar processes

  • Ovoid monomorphic nuclei; conspicuous mitotic activity

  • Areas of myxoid stroma, particularly around vessels

  • IHC: desmin

  • RNA-seq: ZFP64::NCOA3 gene fusion

  • PMID: 35521817

Rhabdomyosarcoma, spindle cell

  • Spindle cell fascicles with variable cellularity

  • Abundant eosinophilic cytoplasm with bipolar processes

  • Ovoid monomorphic nuclei; inconspicuous mitotic activity

  • IHC: desmin, MyoD1; (myogenin negative)

  • RNA-seq: ZFP64::NCOA3 gene fusion

  • PMID: 35521817

Rhabdomyosarcoma, spindle cell

  • Hypocellular spindle cell fascicles

  • Abundant eosinophilic cytoplasm with bipolar processes

  • Ovoid monomorphic nuclei; inconspicuous mitotic activity

  • Areas of hyalinization, particularly around vessels

  • IHC: desmin, MyoD1; (myogenin negative)

  • RNA-seq: ZFP64::NCOA3 gene fusion

  • PMID: 35521817

Rhabdomyosarcoma, spindle cell

  • Short spindle cell fascicles; infiltrating native skeletal muscle

  • Scant eosinophilic cytoplasm with bipolar processes

  • Ovoid monomorphic nuclei; inconspicuous mitotic activity

  • IHC: desmin, myogenin

  • RNA-seq: PPARGC1A::VGLL3 gene fusion

  • PMID: 35766997

Rhabdomyosarcoma, spindle cell

  • Short spindle cell fascicles; infiltrating native skeletal muscle

  • Scant eosinophilic cytoplasm with bipolar processes

  • Ovoid monomorphic nuclei; inconspicuous mitotic activity

  • IHC: desmin, myogenin

  • RNA-seq: EP300::VGLL3 gene fusion

  • PMID: 35766997

Rhabdomyosarcoma, spindle cell

  • Infiltrative

  • Polygonal-spindle cells with vague fascicular-storiform pattern

  • Eosinophilic cytoplasm

  • Ovoid nuclei with occasional multinucleation and moderate pleomorphism; mitotic activity

  • IHC: desmin, myogenin

  • RNA-seq: EP300::VGLL3 gene fusion

  • PMID: 35766997

Rhabdomyosarcoma, spindle cell

  • Spindle cell fascicles

  • Eosinophilic cytoplasm

  • Ovoid-elongated nuclei with prominent nucleoli and mild pleomorphism; occasional mitotic activity

  • Interspersed rhabdomyoblasts with abundant dense eosinophilic cytoplasm and multiple nuclei; occasional thin-walled and ectatic vessels

  • IHC: desmin, myogenin

Rhabdomyosarcoma, spindle cell

  • Spindle cell fascicles

  • Pale amphophilic cytoplasm

  • Hyperchromatic ovoid-elongated nuclei with prominent nucleoli and mild pleomorphism; occasional mitotic activity

  • Interspersed collagenous stroma

  • IHC: desmin, myogenin

Rhabdomyosarcoma, spindle cell

  • Spindle cell fascicles

  • Pale amphophilic cytoplasm with indistinct cell borders

  • Hyperchromatic ovoid-elongated nuclei with mild pleomorphism; occasional mitotic activity

  • Interspersed rhabdomyoblasts with abundant dense eosinophilic cytoplasm; multiple peripheral nuclei; myxoid-collagenous stroma; ectatic thin-walled vasculature

  • IHC: desmin, myogenin