In terms of immunohistochemistry, intestinal-type AC frequently presents the expression of cytokeratin 20 (CK20), mucin 2 (MUC2), caudal-related homeodomain transcription factor 2 (CDX2) and other classically intestinal markers [15,16]; conversely, the pancreaticobiliary subtype has important immunohistochemical analogies with distal cholangiocarcinoma and pancreatic adenocarcinoma, due to the presence of abundant desmoplastic stroma and atypical cells [15,16,17], and the frequent immunohistochemical expression of mucin 1 (MUC1), cytokeratin 7 (CK7), and mucin 5AC (MUC5AC) [15,16,17]. The gene discussed is MUC1; the disease is pancreatic adenocarcinoma.