This case was pathologically proved right adrenal pheochromocytoma.
Pheochromocytomas are rare catechol-amines-secreting tumors. They are considered as paragangliomas and they arise from the chromaffin cells of the adrenal medulla and the sympathetic ganglia. The sympathetic ganglia are found predominantly in the trunk along the pre-vertebral and para-vertebral sympathetic chains and in the connective tissue in or near the walls of pelvic organs, hence the possible location of pheochromocytomas anywhere from the base of the brain to the urinary bladder (2) (5) (7).
About 90% of pheochromocytomas arise within the adrenal glands and about 98% arise within the abdomen. Common extra-adrenal sites are the organ of Zuckerkandl (a), urinary bladder wall, retroperitoneum, heart, mediastinum, as well as carotid and glomus jugulare bodies (7). Pheochromocytomas have been known as the 10 % tumor because: 1- approximately 10 % are bilateral, 2- 10 % are malignant, 3- 10 % occur in children, 4- 10 % are extra-adrenal, 5- 10 % are clinically asymptomatic, 6- 10 % are hereditary (2) (5) (6) (8).
Pheochromocytomas can be associated with multiple endocrine neoplasia syndromes (MEN II and III), von Hippel-Lindau disease (b), von Recklinghausen neurofibromatosis (c), Sturge-Weber syndrome (d), Carney’s triad (e) and may be non-syndromic familial pheochromocytoma (4) (7) (16).
Most common clinical presentation is hypertension (excess catechol-amine release). Other symptoms include tachycardia, sweating, nausea, and chest pain (5). Hypertension may be episodic or refractory in association with the triad of symptoms of palpitations, headaches, and diaphoresis. Biochemical confirmation of pheochromocytoma is of vital importance and should be obtained before imaging. The diagnostic evaluation should include measurement of plasma metanephrine levels and of 24-hour urinary catechol-amine levels (7)
The adrenal glands are two small, yellowish bodies located in the peri-renal space, immediately antero-superior to the upper poles of the kidneys (2). They are composed of a thick outer cortex (90 % of the gland weight) and thinner inner medulla (10 % of the gland weight). The cortex is further sub-divided into three zones: outer zona glomerulosa, middle zona fasciculata, and inner zona reticularis (2). Normal size of adrenal is like crural thickness (< 10 mm) (1).
Diagnosis of pheochromocytoma is dependent on the imaging identification of an appropriately located mass with accompanying clinical and biochemical confirmation (hypertension and elevated urinary vanillylmandelic acid). Characteristically, they appear as solid, soft-tissue masses with attenuation value of more than 10 HU in CT, low signal intensity on T1W and high signal intensity on T2W images in MR. They are typically hyper-vascular (intensely enhanced by iodine based and gadolinium based contrasts). However a wide spectrum of imaging appearances may be seen and pheochromocytomas may mimic almost all other adrenal lesions, both benign and malignant. It may show attenuation value more than 10 in CT and they may be dark on T2W images. Other atypical features include fatty, hemorrhagic, cystic, and calcific changes seen in CT or MR imaging. Various post-contrast appearances can be also seen in these tumors, yet with a characteristic persistent enhancement on delayed phase images (2) (4) (5) (7) (11) (12) (13) (14). The most important MR pulse sequences are in-phase and out-of-phase sequences as drop of signal intensity of the adrenal mass on out-of-phase images compared with on in-phase images is diagnostic of the presence of intracellular lipid (2). Diffusion WI-MRI was studied in adrenal tumors and not found to be significant (3). Punctate signal voids representing tumor vessels in paragangliomas create a salt-and-pepper pattern characteristically seen on T1W and T2W images (7). A major challenge for the noninvasive diagnosis of pheochromocytomas is that any physical contact with these neoplasms can precipitate cardiac arrhythmias and malignant hypertension. Pre-operative diagnosis is of utmost importance and untreated pheochromocytomas can produce fatal clinical consequences (8). Metastatic spread is the only reliable criterion for the diagnosis of malignant pheochromocytoma. Tumor size, mitotic rate, and vascular or capsular invasion are not sufficiently discriminating features to enable the differentiation of benign from malignant tumors. Indiscriminate biopsy of pheochromocytomas may trigger a catastrophic crisis and must be avoided but if percutaneous biopsy is clinically indicated, it should be performed in consultation with endocrine and anesthesia services so that appropriate endocrine blockade and coverage is instituted (2) (7).
Surgical resection is the treatment of choice for pheochromocytoma and usually results in cure of the hypertension. Minimally invasive (laparoscopic) adrenalectomy should be performed for most adrenal pheochromocytomas, with open resection reserved for very large or invasive lesions. Careful preoperative management is required to control blood pressure, correct fluid volume, and prevent intra-operative hypertensive crises. Resection is deemed complete if tested plasma free meta-nephrines 2 weeks postoperatively is within the normal reference range and in such cases, patient survival approaches age-matched controls (17) (18).
(a) Emil Zuckerkandl: an Austrian professor of anatomy (9)
(b) Eugen von Hippel: a German professor of ophthalmology and Arvid Vilhelm Lindau: a Swedish professor of pathology and bacteriology (15)
(c) Friedrich Daniel von Recklinghausen: a German professor of pathology (15)
(d) William Allen Sturge and Frederick Parkes Weber: English professors of medicine (15)
(e) J Aidan Carney: an American professor of pathology (15) (16)