仰臥位により著明な血圧上昇を示した悪性褐色細胞腫の1例

A Case of Malignant Pheochromocytoma Showing Marked Elevation of Blood Pressure at the Supine Position

　症例は57歳，男性．1995年より近医にて高血圧と糖尿病で内服加療中であった．1997年夏より動悸を自覚，心拍数は70／分の洞性整脈で，血圧は250／110mmHgと上昇していた．1997年11月，腹部エコーで右副腎腫瘤を認め，精査のため翌年4月当科に入院した．画像診断上，右副腎に12×12cmの腫瘤と血中・尿中カテコールアミンの異常高値を認め褐色細胞腫と診断した．また，右腸骨にも腫瘤を認め生検上骨転移巣と判断した．入院後発作性血圧上昇と発汗過多があり，24時間血圧測定にて夜間臥床時に著明な血圧上昇を認めた．このため血圧と脈拍モニター下に，坐位から仰臥位への体位変換により血圧が160／80mmHgから270／12mmHgに著明に上昇し，坐位にて前値に戻った．仰臥位により著明な血圧上昇を示した悪性褐色細胞腫の1症例を経験したので報告する．

We describe a 58-year-old male patient with malig-nant pheochromocytoma showing marked elevation of blood pressure at the supine position. He was admitted to the hospital presenting palpitation, headache and sweating associated with striking hypertension up to 250/110 mmHg but without tachycardia. Serum and urinary values of noradrenalin and dopamine were markedly elevated as well as urinary values of vanillyl-manderic acid and normetanephrine. Enhanced comput-ed tomography of the abdomen revealed an enlarged right adrenal gland and an osteolytic tumor mass in the right iliac bone.

By ambulatory blood-pressure monitoring, marked and continuous nocturnal elevation of blood pressure around 200/100 mmHg was noted. As the patient fre-quently had the chief complaints at the supine position, the influence on blood pressure of a posture change from sitting to a supine position was examined. Pronounced elevation of blood pressure from 160/80 mmHg at sit-ting to 270/120 mmHg at a supine position was documented with an increment in serum value of nor-adrenalin. The blood pressure declined to the baseline value after a posture change to sitting.

Following right adrenarectomy, the serum value of noradrenalin was markedly reduced but still exceeded its normal value due to the presence of the metastatic tumor. However, the nocturnal elevation of blood pres-sure disappeared and a postural change from sitting to a supine position did not provoke elevations of blood pressure or serum noradrenalin value. Thus, we conclud-ed that the blood pressure elevation at a supine position was caused by a release of adrenalin from the adrenal tumor. The patient subsequently underwent radiother-apy for the metastatic bone tumor.

An abrupt elevation of blood pressure by an increment in abdominal pressure has been well recognized in pheo-chromocytoma at certain postures such as the lateral position, prone position or on bending, at defecation or urination. However, elevation of blood pressure elicited at a supine position has not yet been described in pheo-chromocytoma. The present case demonstrated that a supine position could cause a striking elevation of blood pressure in pheochromocytoma via the release of nor-adrenalin from an adrenal tumor.