Pancreatic mass as an initial manifestation of polyarteritis nodosa: A case report and review of the literature

Abstract

Classic polyarteritis nodosa (PAN) that targets medium-sized muscular arteries and microscopic polyangiitis (MPA), characterized by inflammation of small-caliber vessels and the presence of circulating myeloperoxidase anti-neutrophil cytoplasmic antibodies (MPO-ANCA), are distinct clinicopathological entities of systemic vasculitis. A 66-year-old woman presented with fever, cholestasis and positive MPO-ANCA. Radiological examination showed a pancreatic mass compressing the bile duct. Therefore, we performed pancreatoduodenectomy. Histopathological examination revealed that necrotizing vasculitis predominantly affecting the medium-sized vessels, spared arterioles or capillaries in the pancreas, a finding consistent with PAN. Unexpectedly, renal biopsy revealed small-caliber vasculitis and glomerulonephritis, supporting MPA. The initial manifestation of a pancreatic mass associated with vasculitis has only been reported in 7 articles. Its diagnosis is challenging because no reliable clinico-radiological findings have been observed. Clinicians should be aware of such cases and early diagnosis followed by immunosuppression is mandatory. Our findings may reflect a polyangiitis overlap syndrome coexisting between pancreatic PAN and renal MPA.

Keywords: Classic polyarteritis nodosa, Microscopic polyangiitis, Myeloperoxidase anti-neutrophil cytoplasmic antibodies, Pancreatic mass, Polyangiitis overlap syndrome

Core tip: A 66-year-old woman presented with a pancreatic mass accompanied by fever, cholestasis and positive myeloperoxidase anti-neutrophil cytoplasmic antibodies. The resected pancreas showed extensive fibrosis associated with necrotizing vasculitis, targeting medium-sized vessels but sparing small-caliber vessels, a finding compatible with polyarteritis nodosa. Unexpectedly, renal biopsy revealed small-caliber vasculitis and glomerulonephritis, supporting microscopic polyangiitis. The initial manifestation of a pancreatic mass associated with vasculitis has only been reported in 7 articles. Although rare, vasculitis should be included in a differential diagnosis for pancreatic masses. Additionally, our findings may reflect a polyangiitis overlap syndrome coexisting between pancreatic polyarteritis nodosa and renal microscopic polyangiitis.