This pancreatic ductal adenocarcinoma shows nuclear loss of DPC4/SMAD4 by immunohistochemical staining. The helpful finding is only present about 60% of the time and was first reported by Wilentz et al. years ago.
Reference: Wilentz RE, Su GH, Dai JL, Sparks AB, Argani P, Sohn TA, Yeo CJ, Kern SE, Hruban RH. Immunohistochemical labeling for dpc4 mirrors genetic status in pancreatic adenocarcinomas: a new marker of DPC4 inactivation. Am J Pathol. 2000 Jan;156(1):37-43. PMID: 10623651