Case Number : Case 1993 - 25 Jan 2018 Posted By: Patrick Shenjere

Good Morning Everyone

We have the virtual slide on this case you can also view:

https://dermpathpro.com/Virtual_Cases_Nov_2017/November_2017/case2.htm

Dear All 

Good morning!

Dr Shenjere's has posted his diagnosis on the case below:

Difficult. It looks like a myxoid variant of DFSP in myxoid areas, and Desmoid in solid areas. My spot in virtual slide is Fibromatosis.

Myxofibrosarcoma (vs nodular fascitis, low grade fibromyxoid sarcoma, myxoid liposarcoma...)

Lobulated myxoid spindle and stellate cell lesion, quite cellular for a myxoid lesion, with arcuate blood vessels

Do not really appreciate lipoblasts in the periphery, so I don't think it's myxoid liposarcoma.

Definitely a low grade sarcoma so don't think it's nodular fasciitis.

Don't see the swirling pattern of spindle cells as commonly seen in low grade fibromyxoid sarcoma. But I would do MUC4 to rule it out.

Just based on morphology, I would agree with dr. Gonzalvo: Low grade myxofibrosarcoma.,

this being a lesion in the groin, would add aggressive angiomyxoma to the above mentioned differentials

Nice example of Evan's tumor (low-grade fibromyxoid sarcoma).

Monomorphic spindle cells featuring hyper- and hypocellular areas in myxoid to hyalinized backgrounds.  Prominent arcades of blood vessels, bland tumor nuclei coming off the BV resemle dribbling candle, there are also halinized collagen balls reminiscent of hyalinizing spindle cell tumor with giant rosettes (in the same disease spectrum, the other one is sclerosing epithelioid fibrosarcoma)

The monotony of the nuclei suggests a translocation (FUS-CREB3L2, or EWSR1-CREB3L1) driven tumor, which essentially rule out another differential diagnosis, myxofibrosarcoma. Myxofibrosarcoma is most seen in limbs of older population (>50yo) and nuclear pleomorphism is usually present. 

Other DDXs I can think of are angiofibroma of soft tissue and perineurioma, which I do not think the current case is.

Like to do MUC4 IHC or FISH to confirm the diagnosis.

I was wrong. LGFMS is a better spot. 

I was thinking myxoid DFSP, but I agree with chugol: low grade fibromyxoid sarcoma

Dear All 

Dr Shenjere's final diagnosis was a myxoid DFSP

Is there IHC and FISH (PDGFB Tx) to support the diagnosis of myxoid DFSP?

DFSP is just a locally aggressive disease. But LGFMS has a metastatic potential and need a long-term follow-up. 

My diagnosis was myxoid DFSP.

The tumour was diffusely positive for CD34 and FISH studies (performed on a biopsy sample from the same tumour) confirmed the presence of COL1A1-PDGFB gene rearrangement. In most cases of myxoid DFSP, one can find more cellular areas with classical DFSP morphology. The lack of storiform architecture in myxoid DFSP can cause diagnostic difficulties in small biopsy material and it is in such cases that one may have to do FISH studies.

Amazing case. DFSP is not common in this location so am glad FISH was done. Somewhat cellular for myxofibrosarcoma. These are really super hypocellular lesion with atypia noted at fairly low power. That being said, much variability in histologic presentation.