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< Presentation of a Case
>
A
26-year-old man was seen at our
outpatient clinic with a 1-year history of hypertension. His
family physician had treated him with doxazocin and diuretics
but had no relief. He was therefore referred to our clinic.
His mean blood pressure was approximately 160/100 mmHg in
the past 3 months.In the preceding six months, he experienced
intermittent headache and palpitation that were sometimes
accompanied by profuse diaphoresis and facial flush. The
symptoms lasted about 5 minutes and resolved later without significant
precipitating or relieving factors for each
episode. On examination, he was fully conscious. The blood
pressure was 158/98 mmHg, pulse 84 /min, temperature 36.5°C,
and respirations 16 breaths per minute. There was no moon
face, buffalo hump, central obesity, purple striae, edema,
abdominal mass or bruit. The patient had no cafe'-au-lait
spots or neurofibroma. Fundoscopic examination showed no
hypertensive retinopathy. He denied a history of smoking, drug
abuse, alcohol consumption, operation or a family history of
endocrine disorders or hypertension.
Under the
impression of secondary hypertension, serial surveys were
performed which are shown in Tables. 24-hour urine examination
showed elevated vanillylmandelic acid (VMA) and catecholamine
levels. Plasma renin activity, aldosterone and cortisol levels
were all within normal ranges. Pheochromocytoma was highly
suspected and he was admitted for further evaluation. Complete
blood counts and biochemical studies, including serum
electrolytes, were within normal limits except elevated
fasting plasma glucose (146 mg/dL). The electrocardiogram
showed sinus tachycardia. Chest radiography revealed no
remarkable cardiomegaly. Magnetic resonance imaging of the
abdomen revealed a left adrenal tumor measuring 3.5 cm in
diameter which revealed hyperintense signal on T2-weighted
image (Figure
1). Whole-body positron emission tomography (PET)
disclosed negative findings. Two weeks before surgery, he was
treated with phenoxybenzamine 150 mg B.I.D, doxazocin 4 mg
B.I.D, and propranolol 10 mg B.I.D. Pre-operative blood
pressure was well controlled between 120/60 mmHg and 150/80
mmHg. Laparoscopic resection of the adrenal tumor was
performed. Histopathological study showed pheochromocytoma (Figure
2
). There was no invasion of the vessels or the
capsule. The post-operative course was uneventful. He became
normotensive without medication after surgery.
< Laboratory data
>
1. Results of the baseline endocrine tests
|
Renin
activity |
aldosterone |
ACTH
(8 am) |
Cortisol
(8 am) |
Cortisol
(4 pm) |
|
1-5 ng/ml/hr |
5-30 ng/dL |
10-65 pg/mL |
5-25 μg/dL |
2.5-12.5 μg/dL |
|
2.54 |
8.58 |
11 |
12.8 |
6.3 |
*** corticotropin＝ACTH
2. 24 hour urine catecholamine and metabolites
|
Dopamine |
Epinephrine |
Norepinephrine |
metanephrine |
VMA |
|
100-440
μg/24h |
<22.4
μg/24h |
11-86
μg/24h |
0-1.0
μg/24h |
1-7
μg/24h |
|
326.88 |
346.21 |
192.07 |
9.87 |
9.94
| *** vanillylmandelic acid=
VMA 3. Figure 1 4. Figure 2
Figure legend of figure 1: there was very high signal
intensity over the Lt adrenal mass on T2 weighted
MRI
Figure legend of figure 2: high-power magnification view of
the pheochromocytoma revealed large cells with abundant pink
granules in cytoplasm.
< 病例解析
>
嗜鉻細胞瘤(pheochromocytoma)是由chromaffin細胞發生的功能性腫瘤。每年每百萬人中約有兩位會發生，是一種極少見的腫瘤。好發在40-50歲，但可以發生在任何年紀；沒有性別上的差異。有10%腫瘤之稱，即10%在腎上腺外、10%有遺傳性、10%兩側性、10%多發性及10%惡性。若是有家族史者，便需要作諸如multiple
endocrine neoplasia type 2 (MEN 2)、Von Hipple-Lindau
disease、Von Recklinghausen's neurofibromatosis type
1等症候群的篩檢。嗜鉻細胞瘤的症候，包括有：高血壓、頭痛、心悸、臉潮紅、多汗、焦燥不安等。其中高血壓有陣發性或持續性，也可能表現出正常的血壓甚至姿態性低血壓，其原因有可能是對catecholamine去敏化(tachyphylaxis)
所致。實驗室診斷可以測血漿和尿液中的catecholamine及其代謝物。一般而言，若血中濃度超過正常上限的3-4倍或24小時尿中濃度超過正常上限的2倍便足以診斷。但若上述血或尿液檢測不符診斷條件仍強烈懷疑的話，進一步可作clonidine壓抑測試及glucagon誘發測試，若前者不能壓制而後者可以提升血中catecholamine的濃度亦可診斷之。除此之外，在其他實驗室數據方面，有的會表現高血鈣、高血色素，而臨床方面，有的會合併庫欣式症候群(Cushing
syndrome)或發燒，原因可能是腫瘤本身可能分泌其他物質，如parathyroid hormone-related
peptide (PTHrP)、紅血球生成素
(EPO)、ACTH或IL-6等而造成上述表現。至於影像學上的定位，電腦斷層、磁振攝影、正子攝影的敏感度大概在80-90%之間，較metaiodobenzylguanidine
(MIBG) scan好。
嗜鉻細胞瘤的治療以手術切除腫瘤為首選，因此病人高血壓的處置多為術前準備及高血壓危症。常用的治療藥物有α受體阻斷劑、鈣離子阻斷劑及可抑制catecholamine合成的metyrosine。值得注意的是，β阻斷劑在未使用α受體阻斷劑前為禁忌，因阻斷β2受體會造成血管收縮而造成高血壓危象。而術前控制血壓的同時也要同時施予靜脈輸液灌注以避免術後腫瘤摘除所造成的低血壓。至於術後，高血壓大部分可痊癒，正如我們的病人的疾病過程。故臨床對有相關症狀或年輕人所罹患的高血壓應提高警覺，及早作篩檢，如此或許可找出罕見的嗜鉻細胞瘤而造福病人甚至挽救性命。
< 參考文獻 >
- Kearney T, Dang C. Diabetic and
endocrine emergencies. Postgrad Med J. 2007
Feb;83(976):79-86.
- Reisch N, Peczkowska M, Januszewicz
A, Neumann HP. Pheochromocytoma: presentation, diagnosis and
treatment. J Hypertens. 2006 Dec;24(12):2331-9
- Ilias I, Pacak K. Diagnosis and management of tumors of
the adrenal medulla. Horm Metab Res. 2005 Dec;37(12):717-21
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Case Discussion
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