Case Number : Case 2206 - 22 November 2018 Posted By: Raul Perret

SFT

Myxoid DFSP

Solitary fibrous tumor

There three histologic subtypes of angioleiomyoma(vascular  leiomyoma): solid, venous and cavernous. Thick vessels in venous but thin in solid variant. Odd age but my first spot is angioleiomyoma.  

I dont have a spot here. Difficult case.

I would add to the differential: Low grade fibromyxoid sarcoma and least likely Myxoid neurofibroma.

myxoid SFT

The vascular pattern is very important in soft tissue tumor in addition to the architecture and cellular cytology. My experience is many soft tissue lesions are just spindle cell tumor so the cytology sometimes does not help. I can see some hemangiopericytoma-like vessels in the tumor so SFT is definitely in the differential diagnosis. So I would do STAT6.

On the other hand, there are too many small capillary-size vessels in the background in addition to the hemangiopericytoma-like vasculature, particularly in Fig 1 and Fig 2. SFT usually does not have so many small vessels like that. So I would like to raise the possibility of a soft tissue angiofibroma in the differential diagnosis. But for sure we need some immunos to guide us.

FiSH NCOA2: absence of rearrangement. 

Rest of IHC panel

EMA : neg
CD34 : neg
SMA : neg
Desmin : neg
Caldesmone : neg
MYOD1 : neg
MDM2 : neg
MUC4 : neg
STAT6 : neg
RP : neg
Ki67 : 2 %

Aggressive angiomyxoma

very much learning case sir

Too cellular for aggressive angiomyxoma. Raul did FISH NCOA2 so I guess he was also considering soft tissue angiofibroma. Actually ER is positive in soft tissue angiofibroma, at least according to one study. Considering that everything else is negative, I would still favor soft tissue angiofibroma in spite of negative FISH NCOA2 (if it's positive, that would be great. If it's negative, it's still Ok because not all soft tissue angiofibromas harbor that translocation).

Yes. After immuno agree with Anh. Although I would have rather preferred leiomioma.  

Thank you for the great comments and particularly to Anh for the great description. I did think this was morphologically a good candidate for soft tissue angiofibroma initially but due to the absence of NCOA2 rearrangement I did not favour it (rearrangement is seen in most tested cases).

In the report, I mentioned this was a benign spindle cell lesion with a prominent vascular component which due to the absence of NCOA2 could represent a cellular angiofibroma.

Cellular angiofibroma and soft tissue angiofibroma are closely related entites showing overlapping morphologic and phenotypic features ref, After your great discussion, I agree that the topography, the branching vessels and variable cellularity are more in keeping with a soft tissue angiofibroma and I should have probably favoured this diagnosis over cellular angiofibroma despite the absence of NCOA2 rearragenment. 

Thank you again for sharing your wise comments that help us learn and become better pathologists.