Pathology: fibroma of tendon sheath
Fibroma of tendon sheath
Spindle-epithelioid cells with vague fascicular pattern
Pale eosinophilic cytoplasm
Monomorphic ovoid nuclei with small nucleoli; inconspicuous mitotic activity
Collagenous stroma; delicate thin-walled vessels
IHC: smooth muscle actin
RNA-seq: negative
Fibroma of tendon sheath
Spindle-stellate cells with storiform-fascicular pattern
Pale eosinophilic cytoplasm
Monomorphic ovoid nuclei with small nucleoli; inconspicuous mitotic activity
Collagenous stroma; delicate thin-walled vessels
IHC: smooth muscle actin
RNA-seq: MYH9::USP6 gene fusion
Fibroma of tendon sheath
Hypocellular; spindle-stellate cells with storiform-fascicular pattern
Eosinophilic cytoplasm
Hyperchromatic ovoid nuclei with occasional multinucleation; rare mitotic activity
Dense collagenous stroma; delicate thin-walled vessels
RNA-seq: MYH9::USP6 gene fusion
PMID: 27125357, 34088995
Fibroma of tendon sheath
Circumscribed; spindle-stellate cells with storiform-fascicular pattern
Eosinophilic cytoplasm
Monomorphic ovoid nuclei with small nucleoli; rare mitotic activity
Dense collagenous stroma; delicate thin-walled vessels
Fibroma of tendon sheath
Circumscribed; spindle-stellate cells with storiform-fascicular pattern
Eosinophilic cytoplasm
Monomorphic ovoid nuclei with hyperchromasia and small nucleoli; inconspicuous mitotic activity
Dense collagenous stroma; delicate thin-walled vessels
IHC: smooth muscle actin
Fibroma of tendon sheath
Circumscribed; spindle-stellate cells with storiform-fascicular pattern
Eosinophilic cytoplasm
Monomorphic ovoid nuclei with hyperchromasia and small nucleoli; inconspicuous mitotic activity
Dense collagenous stroma; delicate thin-walled vessels
IHC: smooth muscle actin