22 July 2005 – Case of the Week #13

 

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We thank Dr. Volkan Adsay, Wayne State University, Department of Pathology and his assistant Olca Baştürk for contributing this case.  We invite you to contribute a Case of the Week by emailing NPernick@PathologyOutlines.com with microscopic images (any size, we will shrink if necessary) in JPG or GIF format, a short clinical history and any other images (gross, immunostains, EM, etc.) that you have and that may be helpful or interesting.  We will write the discussion (unless you want to contribute to it).  We will list you as the contributor, and send you a check for $35 (US) for your time if we use the case.  Please only send cases with a definitive diagnosis. 

 

Case of the Week #13

 

A 31 year old woman presented with a 14 cm pancreatic mass.  Small nodules on the peritoneal surfaces were considered clinically to represent metastatic disease.  Based on the frozen section diagnosis of poorly differentiated endocrine carcinoma of pancreatic origin, the patient underwent subtotal pancreatectomy.

 

Micro images: image #1; #2

 

Immunohistochemistry images:  desmin

 

What is your diagnosis? 

 

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Diagnosis:  Desmoplastic round cell tumor of the pancreas

 

Discussion

 

Desmoplastic round cell tumor is a rare and aggressive tumor of young males, usually of the abdomen or pelvis.  It has also been reported in the pleura, thorax, paratesticular region (Urol Oncol 2005;23:132), kidney (AJSP 2004;28:1379) and CNS, but has not been previously reported (to our knowledge) in the pancreas.  Patients typically present with large, symptomatic masses, and may have widespread peritoneal tumor implants.  The prognosis is usually poor.

 

Histologically, these are small round blue cell tumors composed of solid nests of round/oval cells surrounded by cellular desmoplastic stroma.  There is frequently necrosis, cystic degeneration and glandular arrangements, and the tumors may contain signet ring-like cells, pseudorosettes, rhabdoid cells and spindled cells.

 

These tumors almost always have the translocation t(11;22)(p13;q12), which fuses the WT1 and EWS genes, leading to production of a chimeric protein with transcriptional activity that activates expression of target genes normally repressed by WT1, such as platelet-derived growth factor A and transforming growth factor-beta.

 

These tumors are typically immunoreactive for desmin, keratin (CAM 5.2 or AE1-AE3), WT1 (AJSP 2000;24:830)  and often for PLAP and MIC2/CD99, with variable immunostaining for calretinin, myoglobin, HER2 and c-kit/CD117 (Mod Path 2003;16:229).  The morphology and immunohistochemistry profile are usually sufficient for differentiating from other small blue cell tumors.  If necessary, molecular identification of the characteristic translocation can be performed.

 

Additional references: AJSP 2002;26:823

 

 

Nat Pernick, M.D.
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