April 2022 – Gastroenterology Pathology

An 87-year-old woman with a past medical history significant for invasive bladder cancer was found to have an enlarging mixed solid and cystic lesion in the body/tail of her pancreas on surveillance imaging. She underwent a EUS biopsy and subsequent distal pancreatectomy. The 5.5 cm mass showed the following histology and immunohistochemical profile.

Image: Histology and immunohistochemical profile

This subtype of acinar carcinoma typically harbors alterations in which gene?

  • TP53
  • KRAS
  • MYC
  • RB1

The correct answer is ...


The neoplastic cells coexpress trypsin and neuroendocrine markers without morphologically distinct acinar or neuroendocrine carcinoma components. This neoplasm is best classified as a mixed acinar and neuroendocrine carcinoma (amphicrine type) and is considered a subtype of acinar carcinoma due to shared clinical behavior and genomic features. MYC alterations are present in approximately 55% of pure acinar carcinomas but have been identified in all mixed acinar-neuroendocrine carcinomas investigated. While not associated with a prognostic difference, MYC alterations may play a role in acinar-neuroendocrine differentiation.

TP53, RB1, and KRAS alterations are associated with pancreatic neuroendocrine carcinomas.


  1. Acinar cell carcinoma. In: WHO Classification of Tumours of the Digestive System. 5th ed. IARC Press. 333-335, 2019.
  2. La Rosa S, et al. c-MYC amplification and c-myc protein expression in pancreatic acinar cell carcinomas. New insights into the molecular signature of these rare cancers. Virchows Arch. 2018 Oct;473(4):435-441.
  3. Pancreatic neuroendocrine neoplasms. In: WHO Classification of Tumours of the Digestive System. 5th ed. IARC Press. 343-346, 2019.

Holly Berg, D.O., MLS(ASCP)
Resident, Anatomic and Clinical Pathology
Mayo Clinic

Saba Yasir, M.B.B.S.
Consultant, Anatomic Pathology
Mayo Clinic
Assistant Professor of Laboratory Medicine and Pathology
Mayo Clinic College of Medicine and Science

MCL Education

This post was developed by our Education and Technical Publications Team.