6661 Critical Limb Ischemia - An Unusual Presentation Of A Pheochromocytoma

Abstract Disclosure: S. Hassan: None. Background: Pheochromocytomas can lead to vasoconstriction and its various clinical manifestations due to excess catecholamine release. Critical limb ischemia as a clinical manifestation of pheochromocytoma has been reported sparsely. Clinical Case: A 43 year old female with a past medical history of type 2 diabetes mellitus, Turner syndrome, and hypertension presented to the emergency department with acute on chronic left leg pain. She underwent workup with a CT angiography of the abdomen with runoff for evaluation of her vessels, which revealed an occlusion of her left superficial femoral artery with chronic stenosis of the right femoral system. Multiple unsuccessful attempts were made at revascularization of her left lower extremity, including femoropopliteal bypass, with eventual left above knee amputation, multiple fasciotomies, and angiogram and stenting of multiple vessels. The patient was on a combined OCP (norethindrone-ethinyl estradiol) for hormone replacement for Turner syndrome for the past 30 years, and did not have a personal or family history of clotting disorders. She underwent a hypercoagulable workup which was negative. Echocardiogram was negative for thrombi and was otherwise unremarkable. Incidentally discovered on her initial CT angiography was a heterogeneously enhancing right adrenal mass, which was further delineated on a dedicated CT of the adrenals, which showed a 3.7 cm right adrenal mass with pre-contrast Hounsfield units measuring 46. Biochemical workup revealed a normal plasma renin activity and aldosterone, plasma metanephrine elevated to 5.20 nmol/L (range 0.00 – 0.49 nmol/L), plasma normetanephrine elevated to 4.95 nmol/L (range 0.00 – 0.89 nmol/L), 24 hour urine metanephrine elevated to 3830 ug/d (range 36-229 ug/d), and 24 hour urine normetanephrine 1733 ug/d (range 95 – 650 ug/d). She reports a diagnosis of hypertension at age 36, with no secondary workup pursued; she had suboptimal control on three separate medications, lisinopril, metoprolol, and hydrochlorothiazide. Her blood pressure and heart rate were noted to be labile during her aforementioned surgery. Alpha blockade with doxazosin was started based on her significantly elevated plasma and urine metanephrines and normetanephrines, with improvement in her blood pressure control. She was not found to have a definitive cause of her critical limb ischemia; she was noted to have atherosclerosis in the vessels of her lower extremities, and her chronic oral contraceptive use may also have played a role. However, OCPs are often reported to cause venous rather than arterial thrombi. Therefore, it can be inferred that the catecholamine excess from her presumed pheochromocytoma caused vasoconstriction which may have played a role in the development of her critical limb ischemia. Conclusion: Catecholamine excess that is resultant from a pheochromocytoma may manifest as critical limb ischemia. Presentation: 6/1/2024