Case Number : Case 1780 - 24 March - Dr Richard A Carr Posted By: Guest

Round off your week with another great set of images from Dr Richard A Carr - more to follow in 8 hours  :-)

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Distal type of Epithelioid Sarcoma is my first spot!

This is a neoplastic lesion with lobular growth pattern, compossed by spindle and epithelioid cells, mitotic figures and geographic necrosis with fibrinoid degeneration, central hyalinization. I´m going to buy your Epithelioid Sarcoma Vincenzo Polizzi.

2 hours ago, vincenzo polizzi said:

Distal type of Epithelioid Sarcoma is my first spot!

agree...

Agree, ES. 

Yes lovely example

Agree, too.

Hmm! Full house. Immunos might change your minds (hopefully for me!).

I was going to agree with my colleagues. After Dr. Carr’s allert, maybe immunos might change my mind...

I was going to agree too for an ES. Waiting for the IHC.

If we are fighting against some pathological dark knight like pseudomyogenic hemangioendothelioma I give up immediately...I don't know this new entries in soft tissues tumors...but I'm here for learning!!!

Ok   I'm checking now the IHC. Actin reaction is positive in 30% of ES.  I don't know about Desmin but I think this is an Epithelioid Sarcoma that didn't study immunohistochemistry.  

What about Cytokeratins and EMA?

Epithelioid sarcoma is usually negative for desmin, but reactivity for SMA have been described in the literature. In the absence of the most used immunohistochemical markers (keratin, EMA, vimentin), and considering the clinical history and the microscopic features, I keep my suggestion of epithelioid sarcoma.

If keratin, Ema neg I would think of an odd new entry, like Low Grade Myofibroblastic Sarcoma, but I have never seen it before...I still hope about keratin positivity..

I agree with low grade myofibroblastic sarcoma 

IHC fits with low grade myofibroblastic sarcoma as vincenzo suggested..

I might have to send some more images on Monday. There is not really any necrosis in this case, more hyalinisation. Might I draw attention to the vascular pattern. I don't think the tumour was mitotic to any degree.

Regarding IHC these are my notes: Strong SMA sparing more cellular areas, desmin exact reverse. CD34 highlighting the delicate and branching vessels only. Weak EMA staining in 20% (very capricious stain).

With the recent hint from Dr Carr, shifting to solitary myofibroma?

Yes...why not?! The vascular pattern of half lesion isn't hemangiopericytomatous but could fit well the same...

? sclerotic epithelioid dermatofibroma

Hi, my name is Anh, Dermatopathologist in Orlando, FL. I'm new and this is a great website.

Just a simple question: why can it be just a simple  leiomyosarcoma?

my first thought was solitary myofibroma

Difficult case!...following the immunos, like Mona's suggestion of myofibroma. Biphasic pattern is not particularly prominent but the solitary adult variants may not show this. The other thought which comes to mind is a cutaneous myoepithelioma. The epithelioid cells and hyalinised matrix (? chondroid in last H&E image) along with immunos would fit.  But the vascular pattern noted in this case is not a feature of myoepithelioma.....S100, pankeratins??

Well clearly this case has caused some difficulty!  I should point out that I do not claim myself to be anything other than reasonably adequate at soft tissue lesions but I interpreted this lesion as being in the spectrum of myofibroma/myopericytoma. Clues including the highly cellular areas of rounded / plump epithelioid cells and the more bland spindle cells areas with hyalinised stroma. I think we can see cuffing of the vessels at the periphery of the lesion (highlighted by SMA). Very nice branching vascular pattern fitting with the perivascular (pericytomatous) group. It was also a nicely circumscribed rounded lesion. I had shared the case with Raul Perret previously who thought this lesion could fit with myopericytoma / myofibroma (provided PECOMA, i.e. negative HMB45, excluded). My notes stated S100 and HMB45 was negative. I did not note the keratin staining but presume it was either not done or negative. A well differentiated leiomyosarcoma would really look more like bundles of erector pili (red/pink cytoplasm and longer, cigar shaped, nuclei) with scattered mitotic figures, usually more irregular horizontal permeation (rather than rounded) in outline. Regarding myofibroma I think it can also be one of those pathological dark knights, or perhaps a sheep in wolves clothing, (I had placed a case in the RCPath diploma exam a few years ago and we had to exclude the case from the marking!). I would like to sincerely thank Dr Kathleen Romain for sharing this interesting case with me.