Case Number : Case 1899 - 07 Sept - Dr Richard Carr Posted By: Guest

Dear All Many thanks for your posts. IT are looking at the elusive 'like' button as we did a recent upgrade on the platform. Will hope to have it back soon :). Admin DermpathPRO

I would perform some immunos in this case. To be honest It made me think of that case we saw in Kazakov's collection that looked like Détombes-Rosai-Dorfman disease but was actually a melanoma. Could this be a reticulohistiocytoma/Détombes-Rosai-Dorfman like melanoma? The other important differential is AFX of course

It looks like a balloon cells Melanoma for me too. Thanks for your comment Raul. I’m looking for this RDD-like Melanoma online. 

Also thought of metastatic melanoma (rhabdoid?)

25 minutes ago, vincenzo polizzi said:

It looks like a balloon cells Melanoma for me too. Thanks for your comment Raul. I’m looking for this RDD-like Melanoma online. 

You are welcome Vincenzo, if you find a reference let me know please because I could not find one. I think that if this is a melanoma it deserves to be published.

Metastatic renal clear cell carcinoma is another possibility

5 hours ago, Raul Perret said:

You are welcome Vincenzo, if you find a reference let me know please because I could not find one. I think that if this is a melanoma it deserves to be published.

My first thought was of a balloon cell variant of MM because of nuclear inclusions and nested pattern, but agree with you: AFX is a great ddx, since it is located on a sun exposed region and looks like to a pyogenic granuloma.

I didn't find anything relevant about RD-like MM...

I go along with melanoma for the same reasons listed above. Cells are bizarre, with cytoplasmic variations, including peripheral vacuolization, rhabdoid features and reticulohistiocytoma-like features.

As our colleague Ed Friedlander wrote in his web site: “Celebrate democracy! Today is Brazil’s Independence Day.”

Agree- suspicious of Melanoma resembling RHC.

Agree. Most likely malignant melanoma. Can't rule out a metastasis. History might help.

I'm awaiting x4 additional IHC images but this is the immuno:

Positive: Pan-keratin, Vimentin, PAX8, CD10var.

Negative: CK7, CK20, p63, S100, GCDFP15, TTF1, RCC, WT1

The immunophenotype is consistent with a metastasis of renal cell carcinoma as some of our colleagues suspected

The immunostaining pattern definitely supports a metastatic renal cell carcinoma, although it doesn't look like any typical RCC subtype in the new WHO classification of RCC. So I would like to know what kind of RCC the patient has.  PAX-8 is also positive for thyroid carcinoma (TTF-1 is negative but anaplastic carcinoma may be negative for TTF-1) and carcinoma of the gynecological tract. So still need the history.

5 hours ago, anh said:

The immunostaining pattern definitely supports a metastatic renal cell carcinoma, although it doesn't look like any typical RCC subtype in the new WHO classification of RCC. So I would like to know what kind of RCC the patient has.  PAX-8 is also positive for thyroid carcinoma (TTF-1 is negative but anaplastic carcinoma may be negative for TTF-1) and carcinoma of the gynecological tract. So still need the history.

Ck7 and Ck20 neg with a co-expression of pan ck and vimentin points strongly to kidney (in addition to pax-8). It must be a high grade CCRCC with rhabdoid features

Metastatic RCC. Honostly,before seeing IHC results i thought this is a balloon cell melanoma

Originally my DDx was AFX etc. After seeing the pan-keratin I went for metastatic carcinoma but was still quite perplexed.

Scanning revealed a renal mass in addition to widespread metastases. The additional immunostains performed by colleagues supported a renal primary as discussed eloquently above. 

Thank you for your excellent contributions on the case.

Amazing case. I have just now seen the immunos! Marvelous!. Well done for those who thought of RCC on H&E level!