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    • Surgical Pathology Criteria

    Acinar Cell Carcinoma of the Pancreas

    Definition

    • Carcinoma of the pancreas exhibiting exocrine differentiation and lacking significant (<25%) ductal or endocrine differentiation

    Alternate/Historical Names

    • Acinic cell carcinoma
    • (Note that solid-pseudopapillary neoplasm was erroneously considered in some early reports to be acinar and designated cystic acinar cell carcinoma)

    Diagnostic Criteria

    • Usually grossly circumscribed
      • May have pseudocapsule
      • Frequently has lobular growth pattern
        • Scant stroma within lobules
        • Lacks desmoplastic stroma of ductal adenocarcinoma
    • Most common growth patterns are solid and acinar
      • Solid pattern
        • Sheets and nests of cells
        • May be mixed with acinar pattern
      • Acinar pattern
        • Small lumens surrounded by cells with basal nuclei
      • Glandular and trabecular patterns may occur
      • Cystic variant
        • Innumerable variably sized cysts
        • Termed acinar cell cystadenocarcinoma
      • Intraductal / papillary variant
        • Associated with cystic dilation of ducts
        • Reported cases have better survival
    • Moderate to abundant granular eosinophilic cytoplasm
      • PAS positive diastase resistant
        • May be minimal in some cases
      • Usually apical
    • Uniform vesicular nuclei
      • Large central single nucleolus
      • Usually only moderate nuclear pleomorphism
        • Cases with large pleomorphic cells have been reported
          • No clinical significance
      • Mitotic figures frequent in most cases
      • Nuclei frequently basally located
    • Invasion usually present
      • Vascular and perineural invasion common
      • May invade adjacent tissues and organs
    • Rare histologic variants
      • Oncocytic
      • Signet ring
      • Clear cell
      • Spindle cells (focal)
      • Recognized as acinar based on architectural pattern, nuclear features and presence of classical acinar appearance in other areas
    • Mixed differentiation may occur
      • Each component must comprise at least 25% of the tumor
      • Behavior for mixed neoplasms is similar to pure acinar cell carcinoma
      • Mixed acinar-endocrine requires immunohistochemistry for recognition
      • Mixed acinar-ductal or mixtures of all three may occur

    Robert V Rouse MD
    Department of Pathology
    Stanford University School of Medicine
    Stanford CA 94305-5342

    Original posting/updates:1/2/08, 1/2/12, 2/17/13

    Supplemental studies

    Immunohistology

    Keratin, CK7, CK19 70-100%
    Trypsin 95%
    Chymotrypsin pos
    bcl10 86%
    PDX1 91%
    Lipase freq neg
    AFP variable
    Amylase infrequent
    • Synaptophysin and chromogranin may stain scattered cells
      • If >25% positive, diagnose as mixed acinar-endocrine carcinoma

    Laboratory studies

    • Serum lipase may be markedly elevated
    • AFP may be elevated

    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

    Clinical

    • Rare
      • 1-2% of pancreatic neoplasms
    • Most age 40-70
      • Rare cases do occur in children
    • 10% exhibit lipase hypersecretion syndrome
      • Subcutaneous fat necrosis and polyarthralgia
    • No clinical difference between pure and mixed acinar-neuroendocrine carcinomas
    • Poor prognosis but slightly better than ductal carcinoma
      • 36-72% 5 year survival (La Rosa 2012)

    Grading/Staging/Report

    • No grading scheme for acinar cell carcinoma
    • Staging
      • Use same TNM as ductal adenocarcinoma
    • Prognosis worseif size >6.5 cm, metastases (La Rosa 2012)

    Lists

    Pancreatic Carcinomas

    Pancreatic Acinar Cell Lesions

    Bibliography

    • Hruban RH, Pitman MB, Klimstra DS. Tumors of the Pancreas, Atlas of Tumor Pathology, AFIP Fourth Series, Fascicle 6, 2007.
    • Bosman FT, Carneiro F, Hruban RH, Thiese ND (Eds). WHO Classifiication of Tumors of the Digestive System, IARC, Lyon 2010.
    • Holen KD, Klimstra DS, Hummer A, Gonen M, Conlon K, Brennan M, Saltz LB. Clinical characteristics and outcomes from an institutional series of acinar cell carcinoma of the pancreas and related tumors. J Clin Oncol. 2002 Dec 15;20(24):4673-8.
    • Klimstra DS. Nonductal neoplasms of the pancreas. Mod Pathol. 2007 Feb;20 Suppl 1:S94-112.
    • Basturk O, Zamboni G, Klimstra DS, Capelli P, Andea A, Kamel NS, Adsay NV. Intraductal and papillary variants of acinar cell carcinomas: a new addition to the challenging differential diagnosis of intraductal neoplasms. Am J Surg Pathol. 2007 Mar;31(3):363-70.
    • Klimstra DS, Heffess CS, Oertel JE, Rosai J. Acinar cell carcinoma of the pancreas. A clinicopathologic study of 28 cases. Am J Surg Pathol. 1992 Sep;16(9):815-37.
    • Colombo P, Arizzi C, Roncalli M. Acinar cell cystadenocarcinoma of the pancreas: report of rare case and review of the literature. Hum Pathol. 2004 Dec;35(12):1568-71
    • La Rosa S, Adsay V, Albarello L, Asioli S, Casnedi S, Franzi F, Marando A, Notohara K, Sessa F, Vanoli A, Zhang L, Capella C. Clinicopathologic study of 62 acinar cell carcinomas of the pancreas: insights into the morphology and immunophenotype and search for prognostic markers. Am J Surg Pathol. 2012 Dec;36(12):1782-95.
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