Diagnostic value of serum chromogranin-A combined with MIBG scintigraphy inpatients with adrenal incidentalomas.

Objective: Adrenal incidentalomas (AI) are defined as asymptomatic adrenal masses occasionally discovered during high-resolution imaging procedures, as computed tomography or magnetic resonance. Pheochromocytoma, a chromaffin tumour, must be excluded before any invasive diagnostic or therapeutic procedure, in order to avoid dangerous acute catecholamines-release into blood stream. Chromogranin-A (CgA) is a member of the granin family contained in secretory vesicles of chromaffin system. This study investigated the performance of serum CgA in detecting or excluding pheochromocytoma among patients with AI.

Methods: We enrolled 348 patients by AI > 20 mm without clinical or biochemical signs for corticosteroids overproduction. Serum CgA was assayed by a specific immunoradiometric method and a [123I] metaiodobenzylguanidine (MIBG) scan was performed in the 39 CgA-positive patients.

Results: Eighteen out of these patients showed a positive scan and were submitted to laparoscopic adrenalectomy. Pheochromocytoma was histologically confirmed in all cases . The patients with positive serum CgA, were reassessed 1 year later by clinical examination and serum CgA assay. None of patients developed clinical symptoms of chromaffin-tissue hyperactivity , nor showed a serum CgA increase. Serum levels of CgA were significantly higher inpatients with pheochromocytoma than inpatients without (P<0.0001).

Conclusions: We concluded that serum CgA assay is effective as a single marker to detect or exclude sporadic pheochromocytoma among patients with AI > 20mm. Particularly, a negative serum CgA assay may be used to rule out [123I] MIBG imaging and /or other diagnostic procedures.