The Research Of Clinical And Pathological Chracteristics Of Phaechromocytoma&Paraganglioma With Normal Plasma Free MNs

OBJECTIVE:This study is to explore the clinical and pathological features of pheochromocytoma¶ganglioma(PPGLs) patients with normal plasma free MNs(Metanephrine and Normetanephrine, MNs),and thus increases the diagnostic accuracy of PPGLs patients with atypical clinical features. MATERIALS AND METHODS:The clinical and pathological datas of 189 PPGLs patients were collected. The following aspects of every patient were reviewed, including excessive catecholamine-related clinical symptoms and signs, the 24-hour urinary catecholamine(including epinephrine, norepinephrine, dopamine) and plasma free MNs, the features of tumor on enhanced-contrast CT and radionuclide imaging, the pathological characteristics of tumor(pathological type, diameter, malignant potential). 163 PPGLs patients with solitary mass were also included for being analyzed the expression of tyrosine hydroxylase(TH) and chromogranin A(CGA) in continuous archived pathological specimens. Patients were assigned to Group1 with normal plasma free MNs(both MN and NMN are normal) or Group2 with elevated plasma free MNs(MN, NMN or both are elevated) based on the above tests before operation. The above clinical and pathological characteristics were compared between both groups. RESULTS:24 patients were enrolled into Group1 for comprehensive analysis, while 165 patients were included in Group2. The prevalences of hypertension, paroxysmal hypertension, no less than two aspects of the three classical excessive catecholamine-related symptoms and signs(paroxysmal episodes of headache, sweating and palpitations), weight losses in Group 1 were significantly lower than those of patients in Group2(P<0.05). The average 24-h urinary epinephrine, dopamine and norepinephrine in Group 1 were lower than those of the control group, and the average 24-h urinary norepinephrine in Group1 decreased significantly(p=0.001).The intense heterogenous enhancement was the predominant pattern of PPGLs at enhanced-contrast CT in both groups.There was no significant difference when it came to the prevalences of all enhanced patterns on contrasted CT between both groups(P>0.05), including mild homogeneous enhancement, mild heterogenous enhancement, intense homogeneous enhancement, intense heterogenous enhancement. Radionuclide imaging showed a similar positive detecting rates and diagnostic accuracy between two groups(p=1.000). Both groups included pheochromocytoma, paraganglioma, pheochromocytoma associated with adrenal medullary hyperplasia, composite pheochromocytoma. The difference was not that significant between both groups when it was raleted to the malignant rates of total PPGLs, adrenal masses and extraadrenal masses(p>0.05). In spite of a similar average size of both groups(P>0.05), the PPGLs masses of Group1 in adrenal gland(mean diameter=3.83cm) were significantly smaller than those of control group(mean diameter=5.42cm)(P<0.05). The rates of positive expression of CGA were 100% in Group1 and 97.2% in Group2. The rates of positive expression of TH were 90% in Group1 and 100% in Group2. CONCLUSIONS:The clinical and pathological features of PPGLs patients with normal plasma free MNs included the following aspects :First, the excessive catecholamine-related clinical symptoms and signs were not as classical as PPGLs patients with elevated plasma free MNs; Second, the 24-hour urinary catecholamines were low; Third, the intense heterogenous enhancement at enhanced-contrast CT and positive radionuclide imaging were the major imaging feathers of tumors; Four, most masses in adrenal gland were smaller in PPGLs patients with normal plasma free MNs. Five, both CGA and TH were positively expressed in most tumors, but a tiny minority of malignant paragangliomas may show a negative expression of TH.