Thinking epithelioid hemangioendothelioma?

Atypical fibroxanthoma?

Atypical glomus tumor is my first thought. Second one is epithelioid perineurioma.

Tricky. I wondered about epithelioid cell histiocytoma, PECOMA, epithelioid angiomatous nodule or epithelioid H.E. Like suggestion of glomus - I was wondering about a perivascular type tumour and it also crossed my mind. Needs IHC!

Don't really appreciate cytoplasmic lumen or red blood cells commonly in vascular lesions. Epithelioid histiocytoma?

Dr Chaudhry's response: 

The tumour is negative for S100, p63, EMA, Desmin and AE1AE3. Before I disclose the final immuno results what is your preferred diagnosis? 

Glomus. 

epithelioid glomus

Alk-1?

I was wondering about ALK-1 in this case too. Before answering I would have liked to see H-caldesmon, CD34, ERG, and ki67. For me this is not the expected morphology of Glomus tumor. Without any immunos my first hypothesis would have been epithelioid fibrous hystiocytoma.

Epithelioid fibrous histiocytoma vs epithelioid angiomatous nodule, favouring latter.

Just wonder how much controversy such tumours must have created in the pre- immunostaining days! 

In the preimmunoAge many entities as CEAN ECH PECOMA didn’t exist...:-))

Even usual conditions created controversy. Remember"The Final Diagnosis" by Arthur Hailey?

Yes off course...pathology is the Controversy Science...and the disputes have not been settled by new Ancillary technologies as 

Immuno and Molecular but, if possible, incremented.

Epithelioid fibrous histiocytoma vs epithelioid CEAN vs glomus. ALK, SMA, ERG.

Dr Chaudhry's comments:

Please see the additional immuno!  The tumour is negative for CD10, CD31, Scattered CD68 + cells and low proliferation index for Ki67. 

So the final diagnosis is ........

Very difficult to make sense of the immunohistochemical staining pattern. Most glomus tumors are negative for CD34. But rarely glomus tumors can be positive for CD34 (CD34-positive glomus tumor). That's my best interpretation of this case. But I have never seen one before.

CD34-positive glomus tumor: clinicopathologic and immunohistochemical analysis of six cases with myxoid stromal changes.

Expression of CD34 in glomus tumors.

CD34 positive Glomus sounds good idea!

Solitary fibrous tumor

Dr Chaudhry : Final diagnosis

CD34-positive glomus tumour

Many thanks for the excellent discussion points