Fulminant 'flash' peritoneal carcinomatosis in pancreatic ductal adenocarcinoma: clinical implications of co-occurring oncogenic mutation and tumor suppressor homozygous loss.

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy that frequently presents at an advanced stage. This report describes a case involving a middle-aged male who initially presented with a localised tumour in the pancreatic head accompanied by obstructive symptoms. While he received inpatient management with intravenous fluid hydration, parenteral nutrition and endoscopic stent placement, he subsequently developed an acute abdomen characterised by peritoneal signs. Surgical exploration revealed extensive peritoneal carcinomatosis within 3 weeks, with bowel involvement devoid of necrotic changes. Molecular analysis identified a KRAS G12D mutation and homozygous deletion of the CDKN2A/B tumour suppressor genes. This case exemplifies a hyper-aggressive PDAC phenotype with fatal outcomes, termed 'flash carcinomatosis', whereby tumour biology substantially exceeded standard diagnostic timelines, resulting in a highly truncated course culminating in mortality.