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Pheochromocytoma. Ri 鄢若愚. Introduction. Uncommon neoplasms composed of chromaffin cells which synthesize and release catecholamines Surgically correctable forms of hypertension 0.1% to 0.3% of hypertensive patients have an underlying pheochromocytoma. “ Rule of 10s ".
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Pheochromocytoma Ri 鄢若愚
Introduction • Uncommon neoplasms composed of chromaffin cells which synthesize and release catecholamines • Surgically correctable forms of hypertension • 0.1% to 0.3% of hypertensive patients have an underlying pheochromocytoma
“Rule of 10s" • Association with one of several familial syndromes • Extra-adrenal, occurring in sites such as the organ of Zuckerkandl and the carotid body • Nonfamilial adrenal pheochromocytomas are bilateral • Biologically malignant • Arise in childhood, usually the familial subtypes, and with a strong male preponderance; nonfamilial pheochromocytomas most often occur in adults between 40 and 60 years of age
Clinical Features • Hypertension: often severe, occasionally malignant, and may be resistant to treatment with standard antihypertensive drugs • Paroxysms or Crises: frequent or sporadic, occurring at intervals as long as weeks or months. With time, the paroxysms usually increase in frequency, duration, and severity
Other Distinctive Clinical Features • Increased metabolic rate, such as profuse sweating and mild to moderate weight loss • Sinus tachycardia, sinus bradycardia, supraventricular arrhythmias, and ventricular premature contractions have all been noted. • Angina and acute myocardial infarction
DIAGNOSIS • The diagnosis is established by the demonstration of increased production of catecholamines or catecholamine metabolites. The diagnosis can usually be made by the analysis of a single 24-h urine sample, provided the patient is hypertensive or symptomatic at the time of collection.
Biochemical Tests • Free Catecholamines • Metanephrines and VMA • Plasma Catecholamines • Plasma Metanephrines • Pharmacologic Tests
T2-weighted MR study of a left-sided pheochromocytoma(black arrow). The gallbladder (white arrow) has an increased signal intensity because of its high water content. Pheochromocytomas, adrenocortical carcinomas, and metastatic lesions to the adrenal gland demonstrate this high signal intensity, possibly because of their high water content.
Pre-op (1) Control of hypertension (2) α blockade to prevent intraoperative hypertensive crisis due to tumor manipulation and release of catecholamines (3) Fluid resuscitation to prevent circulatory collapse after removal of the catecholamine-secreting tumor
未有腎上腺素阻斷前，嗜鉻細胞瘤開刀死亡率為24～50%，有了術前α阻斷後，手術死亡率已降為2～3%。目前常用之α阻斷有長效型phenoxybenzamine，一般術前二星期前開始以100mg b.i.d可加至200mg b.i.d 嗜鉻細胞瘤病人高血壓處置 內科醫學會 黃天祥
術前這段期間更需增加血管內容積，可用crystalloid 或生理食鹽水以避免術後發生低血壓，萬一真的發生術後低血壓，可暫用副腎上腺素升壓再逐量去除
Intra-op • Both enflurane and isoflurane have been used successfully. • Intraoperative hypertension: sodium nitroprusside drip, and cardiac arrhythmias are best managed with short-acting β blockers (e.g., esmolol) or lidocaine. • Morphine and phenothiazines may precipitate hypertensive crisis and should be avoided preoperatively
Operation method • Open Adrenalectomy • Anterior Approach • Open Posterior Approach • Laparoscopic Adrenalectomy
Anterior Approach • Wide exposure and access to both adrenals and allows staging of adrenal malignancies • Potentially invasive adrenal tumors. In patients with extremely large (>10 to 15 cm) adrenocortical carcinomas
Exposure is provided by medial visceral rotation of the colon, spleen, and tail of the pancreas.
Open Posterior Approach • Resection of the 12th rib. • In the past, this approach was used primarily for patients with small, unilateral tumors or those who had adrenal hyperplasia and required bilateral adrenalectomy. • Today, the open posterior approach has been almost completely replaced by laparoscopic adrenalectomy. • The only indication currently is the patient with a small (<5 cm) tumor who has contraindications to laparoscopy
The incision is extended inferiorly and laterally from the tenth rib to the posterior iliac crest.
Laparoscopic Adrenalectomy • Preferred method for removal of most adrenal tumors • Decreased postoperative pain medication requirements, shorter hospitalization, fewer complications, and a faster rehabilitation
The anterior and posterior axillary lines, costal margin, and iliac crest are identified by the dashed lines
The adrenal tumor (a), inferior vena cava (c), and liver (l) are visible. Dissection of the connective tissue plane between the inferior vena cava and adrenal is facilitated with a hook electrocautery.
The adrenal gland is indicated by the small arrowheads. Note the inferior phrenic vein (larger arrowheads) entering the left adrenal vein proximal to the latter’s entry into the renal vein
Postoperative Management • Vital signs and urine output. • WBC/DC POD 1 and electrolytes • Glucose monitoring the first 24 hours because of the risk of hypoglycemia from rebound hyperinsulinemia. • After laparoscopic adrenalectomy, liquids are usually begun the morning after surgery and the diet is advanced as tolerated. • Most patients are discharged home within 24 to 48 hours of surgery without restrictions in physical activity.
