Table 4.

Differential diagnosis of BSNS.

Diagnosis	Histology	Immunohistochemistry	Genetics
Schwannoma	Cellular (Antoni A) and microcystic or loosely packed (Antoni B) areas, vessels with perivascular hyalinization	S100 (+), SMA (−), beta-catenin (−), PAX3 (−)	-
Malignant Triton tumor	Nuclear pleomorphism and hyperchromasia, brisk mitotic activity, necrosis	H3K27me3 (−), S100 (+, focal), Myogenin (+), beta-catenin (−), PAX3 (−)	SUZ12 or EED mutation, NF1 mutation
Synovial sarcoma	Dense cellular sheets of uniform spindle-shaped dark blue cells	EMA (+), TLE-1 (+)	SS18-SSX1/2/4
Glomangiopericytoma	Short fascicles and whorls, perivascular accentuation, grenz zone	SMA (+), beta-catenin (−), S100 (−), desmin (−)	CTNNB1 mutations
Solitary fibrous tumor	Patternless growth pattern, variably cellular, ropey collagen bundles	CD34 (+), STAT6 (+), SMA (−), S100 (−)	NAB2-STAT6 fusion
Leiomyosarcoma	Elongated spindle cells with blunt-ended nuclei, perinuclear halos	SMA (+), desmin (+), beta-catenin (−), S100 (−)	-
Fibrosarcoma	Herringbone pattern, usually dense keloid-like collagen	SMA (−/+, focal), desmin (−), S100 (−), beta-catenin (−)	-