Pancreas
Acinar cell tumors
Acinar cell carcinoma

Author: Deepali Jain, M.D. (see Authors page)

Revised: 12 December 2017, last major update August 2012

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

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

Cite this page: Jain, D. Acinar cell carcinoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/pancreasacinar.html. Accessed December 15th, 2017.
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+

Synaptophysin+

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
  • Ductal adenocarcinoma: mucicarmine+, CEA+, negative for acinar markers
  • IPMN: papillary variant of acinar carcinoma, compared to IPMN, has nodules with more sheetlike nature, cuboidal cells, basophilic cytoplasm, prominent nucleoli, apical granules, intraluminal crystals or pale, acidophilic secretions and lack of mucin (Am J Surg Pathol 2007;31:363)
  • Pancreatic endocrine tumor: no acinar differentiation, uniform nuclear morphology, fibrous stroma, PAS-
  • Pancreatoblastoma: children, squamoid bodies
  • Solid pseudopapillary tumor: young women, cystic and hemorrhagic, solid and pseudopapillary patterns, CD56+, CD10+