Pancreas
Exocrine tumors / carcinomas
Adenosquamous carcinoma

Author: Orhun Çığ Taşkın, M.D. (see Authors page)
Editor: Nazmi Volkan Adsay, M.D.
Editorial Board Member Review: Raul S. Gonzalez, M.D.
Deputy Editor Review: Debra Zynger, M.D.

Revised: 21 June 2018, last major update May 2018

Copyright: (c) 2002-2018, PathologyOutlines.com, Inc.

PubMed Search: Adenosquamous carcinoma[TI] pancreas

Cite this page: Taşkın, O.Ç. Adenosquamous carcinoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/pancreasadenosquamous.html. Accessed October 20th, 2018.
Definition / general
Essential features
  • Malignant tumor consisting of both squamous cell carcinoma and ductal adenocarcinoma components
  • 2% of exocrine pancreatic malignancies
  • Adenocarcinoma and squamous components can vary greatly in amount and distribution; some authors require 30% squamous differentiation for the diagnosis of adenosquamous carcinoma
  • p63, p40 and high molecular weight cytokeratin highlight the squamous component
  • Even more aggressive than ductal adenocarcinoma, with a median survival of less than one year
ICD coding
Epidemiology
Sites
Etiology
  • Ionizing radiation of the pancreas may predispose to the occurrence of adenosquamous carcinoma (Mod Pathol 2001;14:443)
Radiology description
Radiology images

Images hosted on PathOut server:

Contributed by Orhun Çığ Taşkın, M.D.

Cystic and necrotic changes

Treatment
Gross description
  • Large, firm mass of the pancreas with ill defined borders, often with necrotic component, with or without cystic areas
  • Some tumors are more demarcated
Microscopic (histologic) description
  • Adenocarcinoma component can have all the characteristics of classic pancreatic ductal adenocarcinoma
  • Squamous component can show keratinization with intercellular bridges or sheets of squamous cells with keratohyalin granules or pearls; some are adenoacanthoma-like with bland, mature squamous elements, whereas others are more basal-like with high N/C ratio and basophilic appearance
  • Adenocarcinoma and squamous components can vary greatly in amount and distribution
  • Presence of a tertiary component has been rarely documented (World J Gastroenterol 2014;20:16381, JOP 2007;8:330)
Microscopic (histologic) images

Images hosted on PathOut server:

Contributed by Orhun Çığ Taşkın, M.D.

Glandular and squamous components

H&E and p63

p63


Contributed by Raul S. Gonzalez, M.D.

Glandular and squamous components



AFIP images:

Adenosquamous carcinoma

Squamous components

Mucoepidermoid pattern

Left: CAM5.2; right: CK13



Images hosted on other servers:

Squamous components

Clear cell component

Rhabdoid component

Keratin stains intermediate filaments of rhabdoid cells

Immunostains


45 year old man with acantholytic pattern, osteoclast-like and pleomorphic giant cells

Cytology description
  • Squamous component may be undersampled but malignant squamous cells are highly significant for the diagnosis (Acta Cytol 2013;57:139)
  • Glandular and squamous components can both be distinguished
  • Dense globules, silhouettes of squamous cells, anucleate squames, atypical cytoplasm and enlarged pyknotic nuclei are present in the prominent necrotic background
  • Sheets and clusters of atypical cells with nuclei of variable sizes and shapes (Cancer 2003;99:372)
Cytology images

Images hosted on PathOut server:

Contributed by Orhun Çığ Taşkın, M.D.

Pap stain

Cell block, H&E

Cell block, p40

Stains
Molecular / cytogenetics description
  • TP53 mutations and 3p loss are commonly encountered
  • KRAS mutations in the majority of cases (Mod Pathol 2001;14:443, Mod Pathol 2009;22:651)
  • Recently discovered "basal-like" molecular subtype of pancreatic ductal adenocarcinoma is believed to also represent adenosquamous carcinoma (Nature 2016;531:47)
  • Both adenomatous and squamous components are believed to originate from the same progenitor cell (J Pathol 2017;243:155)
  • Recent case report documents pancreatic adenosquamous carcinoma arising in intraductal papillary mucinous neoplasm (IPMN) in a CDKN2A germline mutation carrier (World J Gastrointest Oncol 2017;9:390)
Differential diagnosis
Board review question #1
65 year old man presented with back pain and severe weight loss. Radiologic images showed a 4 cm relatively round, lobulated mass with extensive central necrosis in the pancreatic body. He underwent resection. Histologic sections demonstrated conventional ductal adenocarcinoma admixed with sheets of squamous cells with keratohyalin granules and intercellular bridges. Which of the following immunohistochemical stains will be positive in the squamous areas?

  1. β catenin nuclear expression
  2. Chromogranin A
  3. p63
  4. Synaptophysin
  5. Trypsin
Board review answer #1
C. p63