出典(authority):フリー百科事典『ウィキペディア(Wikipedia)』「2013/06/10 07:35:51」(JST)
Pheochromocytoma | |
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Classification and external resources | |
High magnification micrograph of a pheochromocytoma showing the nested arrangement of cells (Zellballen) and stippled chromatin. H&E stain. |
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ICD-10 | D35.0, C74.1 |
ICD-9 | 227.0, 194.0, 255.6 |
ICD-O: | M8700/0 |
OMIM | 171300 |
DiseasesDB | 9912 |
MedlinePlus | 000340 |
eMedicine | med/1816 radio/552 ped/1788 |
MeSH | D010673 |
This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (August 2011) |
A pheochromocytoma (Etymology: Greek "phaios =dark, chroma = color, kytos =cell, oma = tumor") or phaeochromocytoma (PCC) is a neuroendocrine tumor of the medulla of the adrenal glands (originating in the chromaffin cells), or extra-adrenal chromaffin tissue that failed to involute after birth [1] and secretes high amounts of catecholamines, usually noradrenaline (norepinephrine), and adrenaline (epinephrine) to a lesser extent.[2] Extra-adrenal paragangliomas (often described as extra-adrenal pheochromocytomas) are closely related, though less common, tumors that originate in the ganglia of the sympathetic nervous system and are named based upon the primary anatomical site of origin.
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The signs and symptoms of a pheochromocytoma are those of sympathetic nervous system hyperactivity, including:
A pheochromocytoma can also cause resistant arterial hypertension. A pheochromocytoma can be fatal if it causes malignant hypertension, or severely high blood pressure. This hypertension is not well controlled with standard blood pressure medications.
Not all patients experience all of the signs and symptoms listed. The most common presentation is headache, excessive sweating, and increased heart rate, with the attack subsiding in less than one hour.
Tumors may grow very large, but most are smaller than 10 cm.
Up to 25% of pheochromocytomas may be familial. Mutations of the genes VHL, RET, NF1 (Gene 17 Neurofibromatosis type 1), SDHB and SDHD are all known to cause familial pheochromocytoma/extra-adrenal paraganglioma.
Pheochromocytoma is a tumor of the multiple endocrine neoplasia syndrome, type IIA and type IIB (also known as MEN IIA and MEN IIB, respectively). The other component neoplasms of that syndrome include parathyroid adenomas, and medullary thyroid cancer. Mutations in the autosomal RET proto-oncogene drives these malignancies .[3] Common mutations in the RET oncogene may also account for medullary sponge kidney as well.[4]
Pheochromocytoma linked to MEN II can be caused by RET oncogene mutations. Both syndromes are characterized by pheochromocytoma as well as thyroid cancer (thyroid medullary carcinoma). MEN IIA also presents with hyperparathyroidism, while MEN IIB also presents with mucosal neuroma. It is now postulated that Abraham Lincoln suffered from MEN IIB, rather than Marfan's syndrome as previously thought, though this is uncertain.
Pheochromocytoma is also associated with neurofibromatosis.[5]
The diagnosis can be established by measuring catecholamines and metanephrines in plasma (blood) or through a 24-hour urine collection. Care should be taken to rule out other causes of adrenergic (adrenalin-like) excess like hypoglycemia, stress, exercise, and drugs affecting the catecholamines like stimulants, methyldopa, dopamine agonists, or ganglion blocking antihypertensives. Various foodstuffs (e.g. coffee, tea, bananas, chocolate, cocoa, citrus fruits, and vanilla) can also affect the levels of urinary metanephrine and VMA (vanillylmandelic acid).[6]
Imaging by computed tomography or a T2 weighted MRI of the head, neck, and chest, and abdomen can help localize the tumor. Tumors can also be located using an MIBG scan, which is scintigraphy using iodine-123-marked metaiodobenzylguanidine. Even finer localization can be obtained in certain PET scan centers using PET/CT with F-18-fluorodopamine (FDOPA)[7]
Pheochromocytomas occur most often during young-adult to mid-adult life.
These tumors can form a pattern with other endocrine gland cancers which is labeled multiple endocrine neoplasia (MEN). Pheochromocytoma may occur in patients with MEN 2 and MEN 3 (MEN 2B). Von Hippel Lindau patients may also develop these tumors.[8]
Patients experiencing symptoms associated with pheochromocytoma should be aware that it is rare. However, it often goes undiagnosed until autopsy; therefore patients might wisely choose to take steps to provide a physician with important clues, such as recording whether blood pressure changes significantly during episodes of apparent anxiety.
Micrograph of pheochromocytoma.
Micrograph of pheochromocytoma.
Micrograph of pheochromocytoma.
Bilateral pheochromocytoma in MEN2.
Pheochromocytoma. CT abdomen.
Pheochromocytoma. CT abdomen.
In adults, approximately 80% of pheochromocytomas are unilateral and solitary, 10% are bilateral, and 10% are extra-adrenal. In children, a fourth of tumors are bilateral, and an additional fourth are extra-adrenal. Solitary lesions inexplicably favor the right side. Although pheochromocytomas may grow to large size (>3 kg), most weigh <100 g and are <10 cm in diameter. Pheochromocytomas are highly vascular.
The tumors are made up of large, polyhedral, pleomorphic chromaffin cells. Fewer than 10% of these tumors are malignant. As with several other endocrine tumors, malignancy cannot be determined from the histologic appearance; tumors that contain large number of aneuploid or tetraploid cells, as determined by flow cytometry, are more likely to recur. Local invasion of surrounding tissues or distant metastases indicate malignancy.
Extra-adrenal Pheochromocytomas: Extra-adrenal pheochromocytomas usually weigh 20 to 40 g and are <5 cm in diameter. Most are located within the abdomen in association with the celiac, superior mesenteric, inferior mesenteric ganglia and Organ of Zuckerkandl. Approximately 10% are in the thorax, 1% are within the urinary bladder, and less than 3% are in the neck, usually in association with the sympathetic ganglia or the extracranial branches of the ninth cranial nerves.
The differential diagnoses of pheochromocytoma include:
Surgical resection of the tumor is the treatment of first choice, either by open laparotomy or else laparoscopy.[11] Given the complexity of perioperative management, and the potential for catastrophic intra and postoperative complications, such surgery should be performed only at centers experienced in the management of this disorder. In addition to the surgical expertise that such centers can provide, they will also have the necessary endocrine and anesthesia resources. It may also be necessary to carry out adrenalectomy, a complete surgical removal of the affected adrenal gland(s).
Either surgical option requires prior treatment with the non-specific and irreversible alpha adrenoceptor blocker Phenoxybenzamine (Irreversible blockade is important because a massive release of catecholamines from the tumor may overcome a reversible blockade). Doing so permits the surgery to proceed while minimizing the likelihood of severe intraoperative hypertension (as might occur when the tumor is manipulated). Some authorities would recommend that a combined alpha/beta blocker such as labetalol also be given in order to slow the heart rate. Regardless, a "pure" beta blocker such as atenolol must never be used in the presence of a pheochromocytoma due to the risk of such a treatment leading to unopposed alpha agonism and, thus, severe and potentially refractory hypertension.
The patient with pheochromocytoma is invariably volume depleted. In other words, the chronically elevated adrenergic state characteristic of an untreated pheochromocytoma leads to near-total inhibition of renin-angiotensin activity, resulting in excessive fluid loss in the urine and thus reduced blood volume. Hence, once the pheochromocytoma has been resected, thereby removing the major source of circulating catecholamines, a situation arises where there is both very low sympathetic activity and volume depletion. This can result in profound hypotension. Therefore, it is usually advised to "salt load" pheochromocytoma patients before their surgery. This may consist of simple interventions such as consumption of high salt food pre-operatively, direct salt replacement or through the administration of intravenous saline solution.
The massive release of catelcholamines in pheochromocytoma can cause damage to cardiac cells (myocytes).[12] This damage may be due to either compromising the coronary microcirculation or by direct toxic effects on the heart cells.[12]
Pheochromocytoma is seen in between 2–8 in 1,000,000, with approximately 1000 cases diagnosed in United States yearly. It mostly occurs in young or middle age adults, though presents earlier in hereditary cases and it is also called 10% tumor .
In 1886, Felix Fränkel made the first description of a patient with pheochromocytoma. The term "pheochromocytoma" was first coined by Ludwig Pick, a pathologist, in 1912. In 1926, César Roux (in Switzerland) and Charles Horace Mayo (in the U.S.A.) were the first surgeons to successfully remove pheochromocytomas.
In the 1970s, Greene and Tischler derived a line of cells, called the PC12 cell line, from a rat pheochromocytoma.[14]
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リンク元 | 「褐色細胞腫」 |
Location | Phenotype | Phenotype | Gene/Locus | Gene/Locus |
MIM number | MIM number | |||
1p36.22 | Pheochromocytoma | 171300 | KIF1B | 605995 |
1p36.13 | Pheochromocytoma | 171300 | SDHB | 185470 |
2q11.2 | {Pheochromocytoma, susceptibility to} | 171300 | TMEM127 | 613403 |
3p25.3 | Pheochromocytoma | 171300 | VHL | 608537 |
5p13.2 | {Pheochromocytoma, modifier of} | 171300 | GDNF | 600837 |
10q11.21 | Pheochromocytoma | 171300 | RET | 164761 |
11q23.1 | Pheochromocytoma | 171300 | SDHD | 602690 |
14q23.3 | {Pheochromocytoma, susceptibility to} | 171300 | MAX | 154950 |
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