Pathology: embryonal rhabdomyosarcoma

Rhabdomyosarcoma, embryonal

Adolescent; paratesticular

  • Sheets of polygonal-spindle cells

  • Scant amphophilic cytoplasm

  • Round-ovoid nuclei with mild pleomorphism; conspicuous mitotic activity

  • Rare epithelioid-rhabdoid cells with abundant eosinophilic cytoplasm; eccentric nuclei

  • RNA-seq: negative for FOXO1-rearrangement

Rhabdomyosarcoma, embryonal

  • Loose fascicles of spindle-epithelioid cells; condensation below epithelial structures ("botryoides")

  • Bright eosinophilic cytoplasm with long tapering processes; conspicuous "cross-striations"

  • Peripheral nuclei with mild atypia, prominent nucleoli, and occasional multinucleation; occasional mitotic activity

  • Scattered round-polygonal cells with scant cytoplasm; round nuclei with mild pleomorphism

  • RNA-seq: negative for FOXO1-rearrangement

Rhabdomyosarcoma, embryonal

Adolescent; paratesticular

  • Loose fascicles of spindle cell

  • Eosinophilic cytoplasm with long tapering processes; occasional "cross-striations"

  • Round-ovoid nuclei with mild-moderate pleomorphism; conspicuous mitotic activity

  • Scattered epithelioid cells with abundant eosinophilic cytoplasm; eccentric nuclei

  • IHC: desmin, myogenin, MDM2

  • RNA-seq: negative for FOXO1-rearrangement

Rhabdomyosarcoma, embryonal

Adolescent; paratesticular

  • Sheets of spindle-epithelioid cell

  • Amphophilic cytoplasm with occasional delicate tapering processes

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

  • Focal myxoid stroma; necrosis

  • RNA-seq: negative for FOXO1-rearrangement