Surgical Pathology Criteria–

Acinar Cell Carcinoma of the Pancreas

Differential Diagnosis

Acinar Cell Carcinoma of the Pancreas Ductal Adenocarcinoma of the Pancreas
Granular cytoplasm Mucinous cytoplasm
Nuclei round, usually basal, at most moderately pleomorphic Pleomorphic nuclei, may be variably located
Usually solid or acinar formations Large, irregular open ductal formations
Lobular pattern without desmoplastic stroma Desmoplastic stroma
Single, large, central nucleoli Nucleoli variable
BCL10, trypsin, chymotrypsin positive BCL10, trypsin, chymotrypsin negative
Mixed patterns may occur

 

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%

 

Acinar Cell Carcinoma of the Pancreas Poorly Differentiated Pancreatic Neuroendocrine (Islet Cell) Tumor
Granular PASd+ cytoplasm PASd negative
BCL10, trypsin, chymotrypsin positive BCL10, trypsin, chymotrypsin negative
Stromal fibrosis rare Frequent fibrotic stroma
Synaptophysin and chromogranin positivity <25% in pure tumors, mixed tumors may have more Synaptophysin or chromogranin positivity widespread, over 25%

 

Acinar Cell Carcinoma of the Pancreas Solid Pseudopapillary Neoplasm of the Pancreas
Predominantly male Overwhelmingly female
Granular PASd+ cytoplasm PASd+ only scattered globules
Beta-catenin/CD56/CD10 negative Beta-catenin/CD56/CD10 positive
BCL10, trypsin, chymotrypsin positive BCL10, trypsin, chymotrypsin negative
Alpha 1 antitrypsin negative Alpha 1 antitrypsin positive
Keratin positive Keratin variable
Usually infiltrative Usually circumscribed
Lacks pseudopapillary architecture Frequent pseudopapillary architecture
May have true lumens No true lumens
Frequently increased mitotic figures Infrequent mitotic figures
CD99 negative CD99 paranuclear dots (one report)

 

Acinar Cell Carcinoma of the Pancreas Pancreatoblastoma
Typically older patients (40-70 years), rare in children 2/3 <5 years, adult cases mean age 40
Lacks squamoid nests Squamoid nests present
Distinction may not be critical in adults as both are aggressive in adults

 

Serous Microcystic Adenoma Acinar Cell Cystadenocarcinoma of the Pancreas
Lined by clear cells Lined by cells with granular eosinophilic cytoplasm
Frequent central scar Lacks central scar
PAS+, diastase sensitive PAS+, diastase resistant
BCL10, trypsin, chymotrypsin negative BCL10, trypsin, chymotrypsin positive
   

 

Serous Macrocystic / Oligocystic Adenoma Acinar Cell Cystadenocarcinoma of the Pancreas
Lined by clear cells Lined by cells with granular eosinophilic cytoplasm
PAS+, diastase sensitive PAS+, diastase resistant
BCL10, trypsin, chymotrypsin negative BCL10, trypsin, chymotrypsin positive

 

Acinar Cell Cystadenoma of the Pancreas Acinar Cell Cystadenocarcinoma of the Pancreas
Cytologically bland Cytologically moderately atypical with prominent nucleoli
Mitotic figures absent to very rare Mitotic figures frequent
No infiltration Frequently infiltrative
Both are very rare

 

Medullary Carcinoma of the Pancreas Poorly Differentiated Acinar Carcinoma of the Pancreas
Pleomorphic nuclei with variable nucleoli Prominent central nucleoli in most cases
Lipase and trypsin negative Lipase and trypsin positive in most cases
May show microsatellite instability and/or mismatch repair deficiency No mismatch repair defects

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