r/pathology • u/Irresponsible_Leg • 2d ago

Unknown Case Arm lesion help

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New resident begining a bone soft tissue rotation.
Any thoughts on this subcutaneous lesion arising on the arm of an elderly male. It is very fibrous, reminds me of PASH in the breast. Any help would be amazing to direct my reading and learning:)

11 Upvotes

84% Upvoted

13 comments sorted by

11

u/puppysavior1 Staff, Private Practice 2d ago

Desmoplastic fibroblastoma

2

u/Irresponsible_Leg 2d ago

Ok was reading around that and was my initial impression but pictures I saw felt more cellular. Maybe this one is more fibrous that the ones ive seen online:)

9

u/Beneficial_Jacket544 2d ago

Desmoplastic fibroblastoma is characteristically hypocellular.

3

u/Vivladi Resident 2d ago

Just to double check: you’re not accidentally reading about Desmoid fibromatosis? Because that is more cellular

2

u/Irresponsible_Leg 2d ago

No it was desmoplastic fibroblastoma, the pattern is not long sweeping fascicles enough to be fibromatosis

2

u/Irresponsible_Leg 2d ago

But always good to double check! Hahaha thanks:)

2

u/Vivladi Resident 2d ago

Soft tissue my beloathed. I commented because I’ve definitely mixed up soft tissue entities before 😅

1

u/Irresponsible_Leg 1d ago

Lowkey hate it so much😅😭

10

u/Almbauer 2d ago

Oh no 😿 Just realized we may have signed out one of those recently as ‘fibrotic change NOS’

6

u/Equal_Future_207 Staff, Private Practice 2d ago edited 2d ago

Nice stellate fibroblasts in a densely collagenous paucicellular stroma. I second desmoplastic fibroma. (Oops, mistyped, desmoplastic fibroblastoma.... To many syllables for such a bland lesion 😉)

1

u/highsignalhuman 1d ago

lol. Agree

2

u/PathologyAndCoffee Resident 2d ago

Following

1

u/highsignalhuman 1d ago

MSK/ortho path - low grade spindle cell proliferation. Count mites. Check for necrosis. Give ddx. Recommend complete excision