Wunderlich Syndrome as an unusual presentation of Microscopic Polyangiitis: A Case report with Review of Literature.

Wunderlich syndrome, characterized by spontaneous perinephric hematoma with subcapsular extension has been scarcely reported in microscopic polyangiitis (MPA). We report the case of a 45-year-old woman, who presented with constitutional symptoms, left-eye episcleritis, and rapidly progressive glomerulonephritis. She developed sudden, severe left flank pain with hemoglobin drop two days after admission. Both computed tomography (CT) and non-contrast magnetic resonance imaging revealed large left-sided perinephric hematoma. CT angiography failed to demonstrate intrarenal aneurysms. A remarkable reduction in size of her perinephric hematoma was observed after three and a half months of treatment with glucocorticoids and intravenous cyclophosphamide (IV CYC) following the international guidelines. A literature review on renal vessel involvement in antineutrophil cytoplasmic antibody-associated vasculitis revealed 26 case reports and one case series with 20 cases of renal aneurysms. Eighteen cases in the case reports (69.2%) and nine in the case series (45%) ruptured their renal arteries. The majority (44.4%) were managed with IV CYC and high-dose glucocorticoids. Angioembolization, renal replacement therapy, and plasma exchange were used as adjuvant measures. Only three patients (16.7%) underwent nephrectomy, while the majority(63.6%) fully recovered.