Pancreas

Acinar cell lesions

Acinar cell carcinoma


Editorial Board Member: Aaron R. Huber, D.O.
Deputy Editor-in-Chief: Catherine E. Hagen, M.D.
Claudio Luchini, M.D., Ph.D.

Topic Completed: 1 October 2021

Minor changes: 1 October 2021

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PubMed Search: Acinar cell carcinoma[TI] pancreas[TIAB] free full text[sb]

Claudio Luchini, M.D., Ph.D.
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Cite this page: Luchini C. Acinar cell carcinoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/pancreasacinar.html. Accessed October 18th, 2021.
Definition / general
  • Malignant exocrine neoplasm of the pancreas composed of cells with morphological resemblance to acinar cells and with immunohistochemistry positive for acinar markers
Essential features
Terminology
  • Main category: acinar cell carcinoma
  • Subtypes: acinar cell cystoadenocarcinoma, mixed acinar neuroendocrine carcinoma, mixed acinar ductal adenocarcinoma
ICD coding
  • ICD-O: 8550/3 - acinar cell carcinoma
  • ICD-11: 2C10.0 & XH3PG9 - adenocarcinoma of the pancreas & acinar cell carcinoma
Epidemiology
Sites
Pathophysiology
  • Accumulation of genetic alteration, including chromosomal instability and frequent allelic copy number variation
Etiology
  • Tobacco smoking, defective DNA repair; presence of chromosomal instability and frequent allelic copy number variation (Nat Commun 2017;8:1323)
  • Most cases are sporadic but a minority (< 10%) are associated with Lynch syndrome, familial adenomatous polyposis syndrome and Carney complex
Clinical features
  • Presenting symptoms include abdominal or back pain, weight loss, nausea, vomiting; jaundice is more rarely observed than in ductal adenocarcinoma (Am J Surg Pathol 1992;16:815)
  • In the case of extensive metastatic disease, patients may show symptoms related to lipase hypersecretion, including subcutaneous fat necrosis (Front Med (Lausanne) 2015;2:41)
Diagnosis
Laboratory
Radiology description
  • Typical CT and MRI features of pancreatic acinar cell carcinoma: relatively large mass with a well defined margin, exophytic growth and heterogeneous enhancement (J Belg Soc Radiol 2019;103:43)
Prognostic factors
Case reports
Treatment
  • Surgical resection if possible, gemcitabine based chemotherapy / radiofrequency ablation, molecularly based target therapy in the case of actionable alterations (World J Clin Cases 2020;8:1241)
Gross description
  • Well circumscribed mass, at least partially encapsulated, solid and large, with fleshy consistency
Gross images

AFIP images

Cut surface displays large nodules

Frozen section description
  • Hypercellular neoplasm with acinar resembling cells
Microscopic (histologic) description
  • Unlike conventional ductal adenocarcinoma, this tumor is highly cellular and with scant fibrous stroma
  • Cells show moderate amounts of granular eosinophilic cytoplasm containing PAS positive diastase resistant zymogen granules
  • Nuclei are uniform with a typically present, single and prominent nucleolus (Semin Diagn Pathol 2016;33:307)
  • Perineural invasion and vascular invasion are very common
  • Can have different architectures and growth patterns, including cystic, acinar, glandular and intraductal
  • Nonneuroendocrine component of mixed neuroendocrine nonneuroendocrine neoplasms (MiNEN) in the pancreas can be represented by acinar cell carcinoma; MiNEN diagnosis should be based on both morphology and immunohistochemistry
Microscopic (histologic) images

Contributed by Claudio Luchini, M.D., Ph.D.
Typical histology

Typical histology

Intraductal growth

Intraductal growth

Cell detail

Cell detail

Association with neuroendocrine tumors Association with neuroendocrine tumors

Association with neuroendocrine tumors


BCL10 expression pattern

BCL10 expression pattern

Trypsin expression pattern

Trypsin expression pattern

Cytology description
Cytology images

Contributed by Claudio Luchini, M.D., Ph.D.
Cytological aspects

Cytological aspects

Positive stains
Negative stains
Molecular / cytogenetics description
Sample pathology report
  • Distal stomach, duodenum and pancreatic head, pancreaticoduodenectomy (Whipple resection):
    • Acinar cell carcinoma of the pancreas, 2.2 cm
    • Carcinoma involves distal bile duct
    • All margins negative for carcinoma
    • Positive for lymphovascular invasion and perineural invasion
    • Metastatic carcinoma involving 1 of 27 lymph nodes
    • Portion of benign stomach and duodenum with no significant pathologic change
Differential diagnosis
Board review style question #1

A high magnification field of a tumor within the pancreas is shown above. Can the diagnosis of acinar cell carcinoma be based on morphology alone or are other analyses required?

  1. No, morphology alone is always sufficient
  2. Yes, electron microscopy is of great help to rule out a neuroendocrine tumor and is always required
  3. Yes, in addition to morphology, the immunohistochemical demonstration of the acinar differentiation represents the diagnostic gold standard
  4. Yes, molecular analysis is mandatory
  5. Yes, the demonstration of a BRAF rearrangement is required for the diagnosis
Board review style answer #1
C. Yes, in addition to morphology, the immunohistochemical demonstration of the acinar differentiation represents the diagnostic gold standard. Morphology and immunohistochemistry represent the 2 most important tools for the diagnosis. The acinar differentiation seen at histology should be supported with BCL10 and trypsin positivity. Tumor cells are also positive for PASD.

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Reference: Acinar cell carcinoma
Board review style question #2
Is it important to report the intraductal growth pattern of pancreatic acinar cell carcinoma?

  1. No, it is only a descriptive finding
  2. No, this pattern does not belong to the morphological spectrum of acinar cell carcinoma
  3. Yes, this pattern is associated with a better prognosis
  4. Yes, this pattern is associated with a very poor prognosis
  5. Yes, this pattern is associated with intraductal papillary mucinous neoplasm
Board review style answer #2
C. Yes, this pattern is associated with a better prognosis. This pattern represents a potential diagnostic pitfall with intraductal neoplasms (above all, intraductal tubulopapillary neoplasm) and is associated with a better prognosis.

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Reference: Acinar cell carcinoma
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