Case Number : Case 1919 - 06 Oct Dr Arti Bakshi Posted By: Guest

"Tissue culture" of fibroblasts - ? Nodular fasciitis

Multinodular growth pattern. Slit like vessels separating nodules. There aren’t cellular and sclerotic alternating areas, but I think this is a paucicellular hyalinized variant ( or stage ) of Fibroma of tendon sheath. 

would add desmoplastic fibroblastoma to the differentials mentioned above

I like the idea of desmoplastic fibroblastoma. What about beta-catenin immunostain?

Nodular fasciitis?

Desmoplastic fibroblastoma shows thick, hyalinized bands of collagen like in a keloid which are not seen here

Myxoma/ myxoid neurofibroma.

Where's Raul et al when we need them!  I was thinking nodular fasciitis so glad to see Mona on same ticket!

Actually think it might prove to be neurofibroma - plexiform/myxoid and last image shows somewhat distinctive collagen tracts - almost can imagine the axons. S100 please (if negative stick with first spot).

rather difficult based only on these images. Thought of neurofibroma mainly but all the differentials are valid. s-100, EMA, SMA, Desmin, CD34?

I’m still thinking of a TSF. But it could be also a hyalinized variant/stage of myofibroma ( without hemangiopericytomatous areas).  

I am no expert on soft tissue tumours, but i can tell you the immunohistochemical panel. S100, SMA, desmin, CD34 and EMA were all completely negative. So that ruled out neurofibroma and myofibroma. I would have expected some SMA positivity in nodular fasciitis, so did not go for that either. 

I actually left it as a differential of Fibroma of Tendon Sheath and Desmoplastic Fibroblastoma.

I dont think the lesion fits neatly into either, but that's often the frustration with soft tissue lesions! Thanks for all your comments and any further suggestions given the IHC are welcome.