Pathology: PRRX1-rearranged fibroblastic tumour

Variably cellular; spindle-ovoid cells in vague fascicles

Monomorphic ovoid nuclei; inconspicuous mitotic activity

Abundant stroma comprised of thin collagen filaments and occasional collagen rosettes; thin-walled ectatic vasculature with perivascular hyalinization

RNA-seq: PRRX1::NCOA1 gene fusion

Variably cellular; spindle-ovoid cells in vague fascicles

Monomorphic ovoid nuclei; inconspicuous mitotic activity

Abundant stroma comprised of thin collagen filaments; thin-walled ectatic-curvilinear vasculature 

RNA-seq: PRRX1::NCOA1 gene fusion

Variable cellularity; spindle-ovoid cells in vague fascicles and clusters

Eosinophilic cytoplasm

Monomorphic ovoid nuclei; inconspicuous mitotic activity

Abundant stroma comprised of thin collagen filaments; thin-walled ectatic-curvilinear vasculature 

IHC: S100

RNA-seq: PRRX1::NCOA1 gene fusion

PMID: 31008539

Variable cellularity; spindle-ovoid cells in vague fascicles and clusters

Eosinophilic cytoplasm

Monomorphic ovoid nuclei; inconspicuous mitotic activity

Abundant stroma comprised of thin collagen filaments; thin-walled ectatic-curvilinear vasculature 

IHC: S100

RNA-seq: PRRX1::NCOA1 gene fusion

PMID: 31008539

Circumscribed; cellular; spindle-ovoid cells in vague fascicles

Eosinophilic cytoplasm

Monomorphic ovoid nuclei; inconspicuous mitotic activity

Myxoid stroma with prominent thin collagen filaments; thin-walled ectatic-curvilinear vasculature 

RNA-seq: PRRX1::NCOA1 gene fusion

PMID: 31008539