Polyarteritis nodosa presenting with pancreatic-artery rupture and co-existing MEFV and ADA2 mutation: clinicopathological and genomic insights from a case report.

Polyarteritis nodosa (PAN) is an uncommon medium-vessel vasculitis; pancreatic arterial rupture is an exceptionally rare and life-threatening manifestation. A previously healthy 70-year-old man developed progressive abdominal distension followed by haemorrhagic shock due to rupture of a pancreaticoduodenal-artery aneurysm. Staged therapy consisted of coil embolisation, emergency mesenteric-aneurysm resection and, ultimately, pancreaticoduodenectomy. Imaging disclosed multifocal micro-aneurysms in mesenteric, hepatic, renal and gastric arteries, whereas serum amylase peaked at 1036 IU/L, indicating secondary acute pancreatitis. Histology of the resected pancreas demonstrated healed necrotising arteritis with elastic-lamina destruction, transmural fibrosis and recanalised thrombus, fulfilling contemporary diagnostic criteria for PAN. Whole-exome sequencing identified a heterozygous MEFV p.E148Q missense change and three ADA2/CECR1 missense variants (p.H94R, p.H293R, p.H335R) classified as variants of uncertain significance; an intronic UBA1 c.811 + 9C > G substitution and eight synonymous MEFV variants were deemed benign/likely benign. Although none of the detected variants is definitively pathogenic, their coexistence raises the possibility of an additive genetic milieu predisposing to catastrophic vasculitis. This first description of PAN debuting with pancreatic-artery rupture and harbouring overlapping MEFV and ADA2 VUS underscores (i) the need for early vascular imaging in unexplained abdominal haemorrhage, (ii) strict adherence to guideline-based diagnostic algorithms, and (iii) the emerging value of broad genetic screening to refine risk stratification in atypical or fulminant PAN.