Analysis of diagnosis and growth dynamics of adrenal incidentalomas in a large general hospital

Abstract

INTRODUCTION: Adrenal incidentalomas are masses discovered incidentally on imaging studies performed for possible pathologies other than suspected adrenal disease.

AIM: To characterise a cohort of adrenal incidentalomas found on CT.

METHODS: This was a retrospective analysis, taking into account all the adrenal incidentalomas discovered on CT between July and December 2014 at the main hospital in Malta. The adrenal lesions were then classified according to these radiological features. CT scans done prior to and after the study period were also reviewed to establish any change in size of the lesions.

RESULTS: Adrenal incidentalomas were identified in 296 patients, out of 9100 CT scans reviewed. Mean age was 66.9 years (±12.2S.D.). 97 (33%) adrenal lesions could not be classified. Of the remaining 199 incidentalomas, 156 (78%) were confirmed adenomas (Hounsfield units <10, relative or absolute washout values of >40% or 60% respectively), 28 (14%) were metastasis, 12 (6%) myelolipomas, 3 (2%) ganglioneuromas. In the adenoma group, 49.4% were males whereas in the metastasis group 71.4% were males. In the adenoma group, 57% had a left-sided lesion, 34% a right-sided lesion and 9% had bilateral lesions. In the metastasis group 61% had left sided lesions, 21% right sided and 18% bilateral lesions. Largest mean diameter was 20.0 mm (±7.4S.D.) in the adenoma group and 31.1 mm (±18.7S.D.) in the metastasis group (P=0.033). Median follow up in the adenoma group was 46.3 months (ICR 4.9–96.5) whereas in the metastasis group it was 28 months (ICR 0–28.5). Mean change in size was 0.3 mm (S.D. ±2.0) in the adenoma as compared to 20.8 mm (S.D. ±19.7) in the metastasis group (P=0.0001).

CONCLUSION: This study continues to confirm that adrenal adenomas are the commonest adrenal lesion encountered in clinical practice and the majority, remain stable in size over time.