An unusual case of orbital tumor with high renin content and severe hypertension is described. The patient was a 15-year-old girl with juvenile hypertension (200-140 mmHg) associated with right exophthalmos and hypokalemia. The patient showed extremely high levels of plasma renin activity and plasma aldosterone concentration. No difference was present in plasma renin activity from either side of the renal veins. Preoperatively, hypertension responded to treatment with spironolactone. The tumor could not be completely removed because of intracranial metastasis and infiltration, and the hyperreninemia and secondary hyperaldosteronism persisted. The renin content in the orbital tissue was 1,403-2,225 ng/angiotensin I generated/h/g wet weight of tissue. The postmortem histopathologic diagnosis was orbital hemangiopericytoma. This is the first case of extrarenal (ectopic) renin-secreting (or -producing) hemangiopericytoma of the orbital origin. Furthermore this case is worthy of note in the point of view of the presence of the extrarenal renin-angiotensin system, particularly in the brain.</p
