Case Number : CT0030 Adam_Bates

Fibroma of tendon sheath
 

A paucicellular, circumscribed mass of spindled and stellated fibroblasts lying in a dense, amorphous, deeply eosinophilic stroma, in this location, fits well for a collagenous fibroma (desmoplastic fibroblastoma).
 

This lesion has some characteristics that make hard the distinction between desmoplastic fibroblastoma and fibroma of tendon sheath, namely spindled and stellate fibroblasts embedded in a dense fibrocollagenous stroma. Despite the paucity of slitlike vessels, I favor fibroma of tendon sheath because the case history of tendon attachment and the relative hypercellularity. 

I think in fibromas of tendon sheath even the most collagenized areas show more numerous blood vessels and more fibroblasts at least surrounding these vessels. My vote is for collagenous fibroma (desmoplastic fibroblastoma).

Collagenous fibroma (desmoplastic fibroblastoma), mostly based on the stroma, which is more voluminous and hyalinised.

My differential was between fibroma of tendon sheath and desmoplastic fibroflastoma. I couldn't show all the areas, but there were others with more slit-like vessels. So I went with fibroma of tendon sheath.