Pathology: clear cell sarcoma of soft tissue

Clear cell sarcoma

  • Fascicles of spindle-epithelioid cells

  • Pale amphophilic cytoplasm

  • Ovoid nuclei with macronucleoli, vesicular chromatin and mild pleomorphism; mitotic activity

  • Intersecting collagen bands; melanin pigment; multinucleated giant cells

  • RNA-seq: EWSR1::ATF1 gene fusion

Clear cell sarcoma

  • Fascicles of spindle-epithelioid cells

  • Pale amphophilic-clear cytoplasm

  • Ovoid nuclei with macronucleoli, vesicular chromatin and scattered pleomorphism; mitotic activity

  • Occasional collagen bands

  • IHC: S100, SOX10, HMB45, Melan-A

  • RNA-seq: EWSR1::ATF1 gene fusion

Clear cell sarcoma

  • Nests and fascicles of spindle-epithelioid cells

  • Pale amphophilic cytoplasm

  • Monomorphic round-ovoid nuclei with macronucleoli; occasional mitotic activity

  • Intersecting collagen bands

  • IHC: S100, SOX10, HMB45, Melan-A

  • RNA-seq: EWSR1::ATF1 gene fusion

Clear cell sarcoma

  • Fascicles of spindle-epithelioid cells

  • Pale amphophilic cytoplasm

  • Monomorphic round-ovoid nuclei, with macronucleoli; mitotic activity

  • Scattered melanin pigment; intersecting collagen bands and rare multinucleated giant cells

  • IHC: S100, SOX10, HMB45, Melan-A

  • RNA-seq: EWSR1::ATF1 gene fusion

Clear cell sarcoma

  • Fascicles of spindle-epithelioid cells

  • Pale amphophilic cytoplasm

  • Ovoid nuclei, with macronucleoli and moderate pleomorphism; mitotic activity

  • Intersecting collagen bands

  • RNA-seq: EWSR1::ATF1 gene fusion

Clear cell sarcoma

  • Fascicles of spindle-epithelioid cells

  • Pale amphophilic cytoplasm

  • Monomorphic round-ovoid nuclei, with macronucleoli; mitotic activity

  • Intersecting collagen bands; rare multinucleated giant cells

  • IHC: S100, HMB45

  • RNA-seq: EWSR1::ATF1 gene fusion