Autopsy case of microscopic polyangiitis with crescentic glomerulonephritis and necrotizing pancreatitis

Area of Science:

• Nephrology
• Immunology
• Pathology

Background:

• Microscopic polyangiitis (MPA) is a systemic vasculitis often associated with myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA).
• MPA typically affects small blood vessels, leading to glomerulonephritis and pulmonary capillaritis.

Observation:

• An 84-year-old woman presented with rapidly progressive glomerulonephritis (RPGN) secondary to a urinary tract infection, with high MPO-ANCA titers.
• Initial treatment with high-dose intravenous steroids led to clinical recovery and undetectable MPO-ANCA.
• Two months later, the patient experienced severe shock, renal function deterioration, leukocytosis, and disseminated intravascular coagulation (DIC).

Findings:

• Post-mortem examination revealed necrotizing pancreatitis due to acute-stage vasculitis (fibrinoid necrosis of arterioles/venules) and healed crescentic glomerulonephritis.
• Lung examination showed arteriolitis and phlebitis, but not capillaritis or diffuse alveolar hemorrhage.
• The findings suggest necrotizing pancreatitis as an unusual complication of MPA.

Implications:

• This case underscores the importance of considering MPA reactivation irrespective of ANCA titer levels.
• Clinicians should maintain a high index of suspicion for MPA recurrence, even after initial treatment success and normalization of ANCA.
• Necrotizing pancreatitis may represent a rare but severe manifestation of MPA reactivation.