Acinar cell tumors
Acinar cell carcinoma

Author: Deepali Jain, M.D.

Revised: 19 September 2018, last major update August 2012

Copyright: (c) 2002-2017,, Inc.

PubMed Search: Acinar cell carcinoma[TI] pancreas[TI]

Cite this page: Jain, D. Acinar cell carcinoma. website. Accessed November 21st, 2018.
Definition / general
Clinical features
  • 85% men; mean age 62 years (range, 40 - 81 years), rare in children (Am J Surg Pathol 1992;16:815)
  • 10% have lipase hypersecretion syndrome (subcutaneous fat necrosis, polyarthralgias, occasional eosinophilia, nonbacterial thrombotic endocarditis) due to tumor lipase secretion by tumor; these patients usually have liver metastases
  • Tumors may also secrete alpha fetoprotein (AFP) and most AFP+ pancreatic neoplasms are acinar cell carcinomas or pancreatoblastoma (Hum Pathol 2000;31:938)
  • 50% have metastases at diagnosis (liver and regional lymph nodes)
  • 5 year survival is only 10%
  • Variant with intraductal polypoid growth: less aggressive behavior, fewer metastases, smaller size (Am J Surg Pathol 2010;34:1025, Int J Surg Pathol 2011;19:795)
  • Poor prognostic factors: stage III / IV versus I / II (Am J Surg Pathol 2012;36:1782)
Case reports
Gross description
  • Well circumscribed, soft / fleshy (since minimal stroma) with fibrous septa, large (mean 11 cm), hemorrhage and necrosis common
Gross images

Images hosted on PathOut server:

Cut surface displays large nodules separated by fibrous strands, with frequently necrotic foci

Microscopic (histologic) description
  • Note: must document pancreatic enzymes to be considered an acinar cell tumor
  • Highly cellular with minimal stroma and no desmoplasia
  • Solid, nesting, glandular or acinar patterns with sharp luminal space outlines
  • Monotonous, uniform polarized cells with abundant eosinophilic granular apical cytoplasm due to zymogen granules (scanty in solid tumors), basal nuclei and single prominent nucleoli
  • Moderate nuclear atypia, variable mitoses, no mucin
  • Vascular invasion often present
  • 30 - 50% have minor endocrine component based on immunohistochemistry
  • Tumors with solid or trabecular pattern resembles endocrine tumors
Microscopic (histologic) images

Images hosted on PathOut server:

Mixture of acinar, trabecular and solid patterns

Pure acinar pattern resembles normal pancreas

Tumor is markedly cellular with gross lobulation by broad fibrous strands; stroma is scant within large tumor lobules

Nuclei are somewhat irregular in size; nuclei are polarized in acinar formations

Dilated acini form "microglandular" structures

Round cells with
scant cytoplasm,
slightly irregular
nuclei, distinct nucleoli

PAS: tumor cells have abundant, finely granular cytoplasm, which is PAS+ in apical portion

Trypsin stains tumor cells intensely (right side), normal acinar tissue is also typsin+ (right side)

Trypsin stains apical portion of tumor cells

CAM 5.2+


Cytology description
  • Small to moderate sized loose groups with numerous single cells, prominent acinar formation, little anisonucleosis and prominent nucleoli
  • Background cleaner than ductal carcinoma
  • Significant overlap with features of pancreatic endocrine tumors (Diagn Cytopathol 2006;34:367)
Cytology images

Images hosted on other servers:

FNA from metastases to liver

Positive stains
Negative stains
Electron microscopy description
  • Well developed microvilli, abundant granular (rough) ER, numerous mitochondria, zymogen like granules (300 - 600 nm, apical, homogenous), irregular fibrillary granules (up to 3500 nm with fibrillary internal structures, resemble zymogen granules in developing pancreas)
Electron microscopy images

Images hosted on PathOut server:

Tumor cells have many pleomorphic and rather small zymogen granules (mean 400 - 500 nm, range 200 - 1000 nm), commonly oriented towards the luminal space; they are round and lack a hole between their homogeneous dark staining contents and the granule membrane

Images hosted on other servers:

FNA from liver metastasis

Molecular / cytogenetics description
  • Amplifications at chromosome 20q (100%) and 19p (80%) (Mod Pathol 2011;24:1229)
  • Kras and p53 mutations uncommon
  • Biallelic inactivation of LKB1 is associated with Peutz-Jeghers syndrome
Differential diagnosis