Case Number : Case 2308 - 18 April 2019 Posted By: Raul Perret

Angiosarcoma

Epithelioid angiosarcoma; Metastasis from renal cell carcinoma which may be quite vascular

differentials

metastatic tumor-melanoma

angiosarcoma

ALCL

IHC is needed

Metastatic Melanoma vs. Epithelioid Angiosarcoma.

The well defined borders argues against angiosarcoma. I think this is metastatic carcinoma. Ihq are needed

Igor's observation is excellent. Raul said the tumor infiltrates the bone but does not appear to extensively invade the dermis. Is it possible that the tumor actually originates from the bone or brain and grows into the dermis. That would explain the pseudo capsule around the tumor and a hint that the tumor actually does not grow that fast into the dermis although it looks high-grade. Don't see lymphoid tissue under the pseudo capsule to be diagnostic of angiomatoid fibrous histiocytoma. Definitely need IHC and more importantly clinicoradiologic correlation to determine the origin of this tumor. What is the past clinical history? Kind of syncytial look. Malignant meningioma?

7 cm a mass can hardly be a metastasis, however can't be ruled out on morphology. Location, age and looks favor an epithelioid angiosarcoma but the pattern is usually interconnected vessels. Melanoma and clear cell sarcoma are also plausible. 

First thought Metastatic Carcinoma (probably Renal), then if is a primary neoplasm, agree with the differentials, Melanoma and epitheliod Angiosarcoma.

Waiting for de IHC

CD34 was diffusely positive (not shown) 

Proximal type of epithelioid sarcoma - angiomatoid subtype

Agree!  I didn’t even think about it. 

Nice case!. Before IHC, I was thinking epithelioid angiosarcoma!

A nice teaching case 

Final Dx: INI1 deficient neoplasm in keeping with  angiomatoid variant of epithelioid sarcoma. This was a really difficult case because morphology is not typical of ES. I suggested the colleague that shared the case with me to perform INI1 and CD31 because of the vesiculous nuclei that we usually see in angiosarcoma and INI1 deficient neoplasms. I thought CD31 would come positive and INI1 retained but to my surprise it was the opposite.  Hope you liked the case

Great case Raul. Thanks!