Bilateral renal subcapsular hematoma caused by polyarteritis nodosa: a case report.

Polyarteritis nodosa, which is a systemic vasculitis of small- and medium-sized arteries, can cause arterial aneurysms in various organs, sometimes resulting in aneurysm rupture and hemorrhage. A kidney is one of the major targets of polyarteritis nodosa. Here, we report a 73-year-old woman who presented with sudden-onset high fever, diarrhea, and renal injury with bilateral renal subcapsular hematoma shown on contrast-enhanced computed tomography scan. She did not have trauma and significant medical history other than breast cancer in remission. Serological and immunological tests except for anti-Sjögren's syndrome-A and anti-Sjögren's syndrome-B were all negative. Digital subtraction angiography revealed bilateral intrarenal micro aneurysms, which allowed us to diagnose the patient with polyarteritis nodosa. As continuous monitoring of bilateral intrarenal hematoma by ultrasonography and computed tomography scan did not detect progression of intrarenal hemorrhage and extra renal hematoma, transcatheter arterial embolization and nephrectomy were not performed. Although hemodialysis therapy was required temporarily for acute kidney injury with anuria, her general condition and kidney function remarkably improved after receiving systemic immunosuppressive therapy with corticosteroids and cyclophosphamide. In conclusion, this is a rare case of polyarteritis nodosa manifesting as spontaneous bilateral subcapsular renal hemorrhage with deteriorated renal function, which was successfully treated with immunosuppressive therapy.