Endocrine Abstracts

Background: Up to 30% of incidentally-discovered adrenal masses are lipid-poor adenomas (LPA). The clinical significance of LPA is poorly understood. The aim of the study was to investigate histopathological features of LPA and their association with radiological parameters.

Methods: A total of 39 patients with radiological evidence of LPA were included. LPA was defined as an adrenal mass with pre-contrast Hounsfield units (HU) ≧10, associated with absolute washout >60% or relative washout >40% after contrast infusion. Patients underwent hormonal work-up for primary aldosteronism (aldosterone/plasma renin activity ratio >30 in orthostatic position and after Captopril test) and pheochromocytoma (elevated urinary metanephrines). Hypercortisolism was defined as cortisol levels after 1 mg-dexamethasone suppression test >50 nmol/l. F18-Fluoro-Deoxy-Glucose (FDG)-PET scan was performed in 31/39 patients. In resected tumors, Weiss, Lin-Weiss-Bisceglia, and PASS score were calculated, where appropriate.

Results: Radiological characteristics of the population were as follows (mean±SD): tumor diameter 23.0±10.9 mm, pre-contrast density 27.5±10.2HU, absolute and relative washout 68.1±7.6% and 50.7±7.5%, respectively, and FDG-PET scan 6.1±4.6 SUV. Hormonal evaluation showed Cushing’s syndrome in 7/39 patients (18%), subclinical hypercortisolism in 11/39 subjects (28%), primary aldosteronism in 2/39 patients (5%) and elevated metanephrines in 2/39 subjects (5%). The remaining cases (17/39, 44%) were non-secreting. Eighteen patients underwent adrenalectomy because of tumor diameter (n=2), hormonal hypersecretion (n=9) and high FDG-PET SUV (n=7). Histopathological examination showed adrenocortical adenoma in 12/18 cases (66%) and adrenocortical carcinoma in 3/18 tumors (17%), as defined by Weiss score. Hemangioma was diagnosed in 1/18 cases. The two remaining tumors were pheochromocytoma (PASS score 3 and 7). Among all adrenocortical tumors, abundant granular eosinophilic cytoplasm was found in 11/15 cases (73%). By applying the Lin-Weiss-Bisceglia score, one tumor was confirmed malignant, whereas 3/11 tumors were borderline. Weiss score was positively associated with pre-contrast density (Odds Ratio [OR] 1.088, 95% Confidence Interval (CI) 1.018–1.163, P=0.013) and absolute washout (OR 1.105, 95%CI 1.005–1.216, P=0.039). Lin-Weiss-Bisceglia score was positively associated with tumor diameter (OR 1.045, 95%CI 1.015–1.076, P=0.003) and pre-contrast density (OR 1.046, 95%CI 1.002–1.091, P=0.039).

Conclusion: LPA represents a heterogeneous class of tumors, which may include pheochromocytoma and adrenocortical carcinoma. In our pilot study, 5/18 (28%) LPAs were classified as malignant or borderline at histopathological analysis. Eosinophilic cytoplasm is a common finding in those tumors and Lin-Weiss-Bisceglia score may be used to avoid overdiagnosis of malignancy.