Spindle-epithelioid cells arranged in nests
Eosinophilic cytoplasm
Round-ovoid nuclei with small nucleoli; occasional multinucleation; mitotic activity
Myxohyaline stroma
IHC: keratin (AE1/AE3), p63
RNA-seq: EML4::NTRK3 gene fusion
Spindle cells with fascicular-storiform pattern
Pale eosinophilic cytoplasm
Ovoid nuclei with small nucleoli; mitotic activity
Collagenous stroma
IHC: S100, CD34, MDM2
RNA-seq: TPM3::NTRK1 gene fusion
Lobulated; spindle-stellate-epithelioid with fascicular-patternless arrangement
Pale amphophilic cytoplasm
Ovoid-round nuclei with mild pleomorphism and occasional multinucleation; occasional mitotic activity
Variable myxoid-collagenous stroma; prominent ramifying capillary vasculature
IHC: CD34, S100
RNA-seq: LMNA::NTRK1 gene fusion
PMID: 32050835
Spindle cells with herringbone-storiform pattern
Eosinophilic cytoplasm with long tapering processes
Ovoid and elongated nuclei with mild atypia; mitotic activity
Scant myxoid-collagenous stroma and a prominent ectatic thin-walled vasculature
IHC: CD34, S100
RNA-seq: TPM3::NTRK1 gene fusion
Lobulated; spindle-epithelioid cells with vague fascicular pattern
Abundant eosinophilic cytoplasm with indistinct cell borders
Ovoid and elongated nuclei with a tapering end, prominent small nucleoli, marked pleomorphism and frequent multinucleation; mitotic activity
Fibromyxoid stroma with occasional bundles of collagen and a mildinfiltrate of lymphocytes and eosinophils
IHC: panTRK (negative)
RNA-seq: HDGFRP3-NTRK3 gene fusion*
* To date unreported in the literature
Infiltrative; spindle-stellate cells with fascicular-storiform pattern
Pale amphophilic cytoplasm
Ovoid-round nuclei with minimal pleomorphism; inconspicuous mitotic activity
Myxoid-collagenous stroma; prominent capillary-like vasculature
RNA-seq: LMNA::NTRK1 gene fusion