Case Number : Case 2483- 10 January 2020 Posted By: Dr. Richard Carr

Malignant tumor!  Spindle Cell SCC? Leiomyosarcoma? Myoepithelial Carcinoma? 

Looks like an angioleiomyoma in some of the images...PEComa also a consideration. 

Could it be a solitary fibrous tumor??? There are some ramified vessels here and there

This case is impossible. But I like some of the suggestions. I was thinking about a malignant myopericytoma / perivascular tumour. However it turns out the patient had a past history of renal cell carcinoma with partial sarcomatoid transformation. We therefore favoured a metastasis from the sarcomatoid component of renal cell carcinoma. The case was seen by Chris Fletcher who found multi-focal EMA positivity but stains for pan-keratin, Cam5.2, CK5, PAX8 and p63 were negative. Chris Fletcher comments: "In my experience, it is quite unusual for carcinomas to express EMA in the absence of keratin, but renal cell carcinoma is one of the few in which I have seen this previously. Now that you have shared with me images of sarcomatoid areas in the original renal cell carcinoma then, although the degree of nuclear atypia seems to be less in this lesion than in the primary tumor, nevertheless I think it would be reasonable to label this as a malignant epithelioid and spindle cell neoplasm, in context most suggestive of metastatic sarcomatoid renal cell carcinoma."

When I saw the images, I was sure of one thing! Solving this case is impossible with HE alone!!! So I preferred to wait and c... Nice case, thank you Dr Carr for sharing.  

One of my thoughts was also malignant myopericytoma / perivascular tumor, but it couldn't explain the other pathological features! Impossible case as said. Thanks for sharing. One learns.

great case sir

It tells us to get clinical information in unusual cases

Always Nice to see such difficult cases. Thanks for sharing