Surgical Pathology Criteria–

Well Differentiated Pancreatic Neuroendocrine Tumor / Islet Cell Tumor

Differential Diagnosis

Acinar Cell Carcinoma of the Pancreas Well Differentiated Pancreatic Neuroendocrine (Islet Cell) Tumor
Granular PASd+ cytoplasm PASd negative
Basal nuclear polarization Centrally located nuclei
Vesicular nuclei with prominent nucleoli Salt and pepper stippled chromatin
BCL10, trypsin, chymotrypsin positive BCL10, trypsin, chymotrypsin negative
Synaptophysin and chromogranin positivity <25% in pure tumors, mixed tumors may have more Synaptophysin or chromogranin positivity widespread, over 25%

 

Well Differentiated Pancreatic Neuroendocrine (Islet Cell) Tumor Solid Pseudopapillary Neoplasm of the Pancreas
Lacks pseudopapillary architecture Frequent pseudopapillary architecture
Chromogranin usually strongly positive Chromogranin focal to negative
Keratin positive Keratin variable
Galectin 3 negative Galectin 3 positive (small numbers)
Vimentin, CD10 negative Vimentin, CD10 positive
Nuclear beta catenin negative Nuclear beta catenin positive
No PAS+ granules in cytoplasm PAS+ granules may be present
CD99 variable but not paranuclear dots CD99 paranuclear dots (one report)
Solid pseudopapillary neoplasm may be synaptophysin positive

 

Pancreatoblastoma Well Differentiated Pancreatic Neuroendocrine (Islet Cell) Tumor
Trypsin, chymotrypsin positive Trypsin, chymotrypsin negative
Squamoid nests always present Lacks squamous differentiation
Usually prominent nucleoli Salt and pepper chromatin
Chromogranin, synaptophysin scattered positive Chromogranin or synaptophysin widespread staining
Islet polypeptide markers negative or very focal Islet polypeptide markers frequently positive
Cellular stroma frequent Lacks cellular stroma

 

Large Cell Poorly Differentiated Pancreatic Neuroendocrine Carcinoma Well Differentiated Pancreatic Neuroendocrine (Islet Cell) Tumor
Mitotic rate >20/10 hpf Mitotic rate not over 20/10 hpf
May have extensive necrosis Lacks extensive necrosis
Small cell poorly differentiated neuroendocrine carcinoma bears no resemblance to well differentiated neuroendocrine neoplasm

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