Good Grief, not easy. Well, it is not an adenoma.

----Comment by: PathDoc15 on 10/18/2007 12:30:38 PM

Ok, seriously, it doesn't look epithelial but I would get the stains anyway (pan CK, CK20, CK7). It could be soft tissue tumor sarcoma. I would get smooth muscle markers (sma) also an endothelial marker (unlikely - XIIIa, cd31, CD34) also HHV8 (for some reason I want this to be Kaposis Sarcoma even though it isn't). Even though not pigemented, it could be melanoma - would not want to miss that. Then I come to the realm of just guessing. Perhaps the pathologypics army can help out?

----Comment by: PathDoc15 on 10/18/2007 12:36:25 PM

No idea - but its definitely not Kaposis sarcoma, definitely.

----Comment by: PathDoc15 on 10/19/2007 8:01:23 AM

How about a ganglioneuroma?

----Comment by: kyouens on 10/19/2007 5:13:45 PM

Other thoughts...Langerhans histiocytosis or malignant histiocytic tumor (dendritic sarcoma), Hodgkin or other heme-malignancy, malignanct granular cell tumor, CD117-negative GIST. If ganglioneuroma, how about a GFAP NFP.

----Comment by: Navypathdoc159 on 10/23/2007 6:27:04 AM

I was going to say earlier - the most common S100 positive polyps I see are granular cell tumors and ganglioneuromas, and this tumor doesnt really look like those - there are some huge malignant cells which may not be apparent on the image. This case just went to an unnamed big-gun for diagnosis. I will let you know the results as soon as they are available. Full immunoprofile as done by me: CK-, aSMA-, desmin-, C-kit -, s-100 , mart1-, hmb45-, calretinin-, cd31-, cd34-, NSE-, vimentin weak, CD1a -, cd68 -, and Ki67 index around 10 percent. Thanks for all your input.

----Comment by: GIPathDoc on 10/24/2007 8:31:02 AM

Well WHAT IS IT. I cant sleep at night anymore I MUST KNOW. ;)

----Comment by: PathDoc15 on 10/26/2007 7:54:23 AM

OK, I just got a terrific, educational consultation back. I wish I could advertise for the consultant, but alas, I will refrain. Let me paraphrase the letter: a subset of tumor cells show quite striking nuclear atypia which is degenerative in nature. Mitotic activity and necrosis are not apparent. S-100 positive, GFAP positive supports benign schwannoma with degenerative nuclear atypia. Schwannomas of the GI tract are typically not encapsulated, in contrast to when they are seen in conventional soft tissue locations. Local recurrence is unlikely. Wow.

----Comment by: GIPathDoc on 11/2/2007 11:46:36 AM

I think I might have gone down the tubes on this one. The nuclear atypia is quite striking.

----Comment by: PathDOc15 on 11/2/2007 11:58:28 AM

Amen, brother. This is why we send things out for consultation. Certainly didn't look like the schwannomas I studied for the boards. In any case, GI schwannomas, according to Dr. Odze's book, are more common in the stomach and rare in the esophagus or intestines. They peak in patients in their 50's. They are not associated with neurofibromatosis. Verocay bodies may be present but are often inconspicuous. They may have a few cells with nuclear atypia, but the mitotic count is usually less than 5 50hpfs. Rare cases show prominent epithelioid cells.

----Comment by: GIPathDoc on 11/2/2007 12:14:27 PM

Wow. This was a great case. Thanks for the followup GIPathDoc.

----Comment by: kyouens on 11/2/2007 1:51:03 PM

I am surprised at how large and atypical these nuclei are for a benign lesion. I wonder if this is typical for degenerative change?

----Comment by: PathDoc15 on 3/20/2008 12:34:18 PM

Morphologically, this is not a schwannoma. In my opinion, a strongly S100-positive tumor with this morphology is melanoma "until proven otherwise". Someone needs to do a physical on this patient.

----Comment by: apath on 8/15/2008 11:23:37 PM

A former GI faculty member brought a similar case to us for a show and tell one morning. Her case was similar in terms of atypia. She had it sent to CDF at Mass Gen who called it an ancient schwannoma. Her case was a little more circumscribed, but still unencapsulated.

----Comment by: Iago on 8/16/2008 8:08:35 AM

Okay, in the absence of mitotic activity or necrosis, a metastatic melanoma goes lower on the differential. Personally, I would not sign it out as schwannoma above the line. Moreover, I would recommend close clinical follow-up. Remember, the experts are not always right. I recently had a case of a gastric biopsy that was read by an expert as a poorly-differentiated carcinoma, based on a somewhat discohesive growth pattern in the lamina propria and cytokeratin immunoreactivity. Amazingly, this same expert read a gastric biopsy from the same patient one month prior, and called it a carcinoid tumor. I got the block on the second biopsy and found that it was strongly immunoreactive for synaptophysin and chromogranin. There was no mitotic activity or necrosis, and the tumor certainly was not a small cell carcinoma (which is essentially a poorly-differentiated neuroendocrine carcinoma). Thus, the tumor was actually a carcinoid tumor. Sometimes the experts go too fast. The bottom line is to always maintain a healthy sense of skepticism, even with the experts.

----Comment by: apath on 8/16/2008 9:31:23 AM

good advice apath.

----Comment by: Iago on 8/16/2008 2:43:43 PM