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Case History

72 years female with a history of acral melanoma presented with loss of appetite, a mass in pancreatic head and multiple small nodules in peripancreatic fat.  Endoscopic ultrasound fine needle aspiration was performed.

1. Based on Diff-Quick stain smears rank the following diagnosis from most likely to unlikely:

• -Solid pseudopapillary carcinoma
• -Carcinoid tumor
• -Islet cell tumor 
• -Acinar carcinoma
• -Poorly differentiated ductal carcinoma

1. Positive staining for neuroendocrine markers likely exclude (mark true or false):

• -Solid pseudopapillary carcinoma
• -Carcinoid tumor
• -Islet cell tumor 
• -Acinar carcinoma
• -Poorly differentiated ductal carcinoma

1. Although not frequently used, electron microscopy can differentiate between (mark true or false):

• -Insulinoma and carcinoid
• -Acinar carcinoma and ductal carcinoma
• -Solid pseudopapillary carcinoma and Islet cell tumor
• -Acinar carcinoma and carcinoid 
• -Metastatic melanoma and poorly differentiated carcinoma
  

 IHC positive staining for trypsin

Electron microscopy image showing zymogen granules H&E-stained section showing metastatic acinar carcinoma in lymph node

1. Answers:

   1: 
   1- Acinic carcinoma
   2- Carcinoid tumor
   3- Islet cell tumor
   4- SPN
   5- Poorly differentiated carcinoma

2. 2:
   1- False
   2- False
   3- False
   4- False
   5- True

3. 3:
   1- True
   2- True
   3-True
   4-True
   5-True

4. Stains for endocrine markers were negative.  Stain for trypsin was positive.  Electron microscopic examination shows classical zymogen granules.   Final diagnosis acinic carcinoma with metastasis to lymph nodes.