Hyperreninemic hypertension secondary to a subcapsular perinephric hematoma in a patient with polyarteritis nodosa.

Page kidney is the name ascribed to a rare syndrome of hyperreninemic hypertension caused by unilateral compressive perinephritis. Blood or fluid that accumulates in the perinephric subcapsular space compresses the renal parenchyma leading to ischemia. This syndrome is analogous to the description of cellophane-induced perinephritis by Page in 1939. Page kidney typically presents in healthy young men after blunt trauma to the flank or abdomen, although cases have been noted after medical or surgical interventions. We report a case of a Page kidney in a young man with hepatitis B virus-associated polyarteritis nodosa. The patient presented with severe hypertension, hypokalemia, hyperreninemia, and radiographic evidence of a unilateral subcapsular hematoma. Perinephric hemorrhage developed because of necrotizing vascular inflammation and spontaneous or traumatic vascular rupture. In patients who present with new-onset hypertension and hypokalemia with a history of trauma or coexisting vasculitis, the presence of a Page kidney should be considered.