PREDICTIVE VALUE OF CHROMOGRANIN A IN A DIAGNOSIS TOWARDS PHEOCHROMOCYTOMA IN ADRENAL INCIDENTALOMA.

Abstract

Some adrenal tumors, such as pheochromocytoma, can be life-threatening. Therefore it is crucial to distinguish them from other lesions, especially prior to surgery. Chromogranin A (CgA) seems to potentially be a good marker for tumors of chromaffin origin. To assess the differentiating value of CgA in the diagnostic work-up of pheochromocytoma. Retrospective study of operated patients with adrenal incidentaloma with lesions > 10 Hounsfield's units (HU) on CT. Thirty patients (11 males, 19 females; aged 61.5±21 years) were enrolled in the study. Patients using medications interfering with the assessment of CgA and metanephrines were excluded. Two groups were formed: those with pheochromocytoma (Ph, n=16) and those with non-pheochromocytoma (N-Ph, n=14) lesions. Data included radiological features of masses, serum CgA and 24-hour urine metanephrines (24 - HUM) concentrations. No difference in 24-HUM level nor tumor size or density was found between groups Ph and N-Ph. Median serum CgA concentration was higher in Ph group compared to the N-Ph: 99.35 (68.12-172.73) vs. 52.92 (34.37-101.26) ng/mL, respectively (P=0.04). In Ph group, the size of the lesion correlated negatively with density (r= -0.53, P=0.042). No significant correlation in CgA, 24-HUM, density or size of the lesion was found. Performed curve receiver operating characteristic (ROC) showed AUC=0.7232 for CgA. Taking into account CgA serum value of ≤ 50 ng/mL (sensitivity: 93.75%, specificity: 50.00%, P=0.012), we proposed an algorithm for management of lesions > 10 HU on CT. CgA level ≤ 50 ng/mL might be useful in initial screening evidence for the exclusion of pheochromocytoma. It is crucial to eliminate factors interfering with the measurements.