Endocrine Abstracts

Widespread use of CT and MRI scan has led to the identification of incidental adrenal tumours. The need to determine functionality often results in a battery of investigations that are a drain to scarce resources and are frequently normal. Studies to identify tumour radiological features that suggest functionality and hence enable targeted investigations are few in the literature. To this effect we set out to analyse which features on imaging that are best predictive of functionality.

We retrospectively reviewed 17 patients who have been diagnosed with an incidental adrenal mass. The imaging features and endocrine investigations carried out on these patients were noted and data on patients with functional tumours (F) were compared with those with non-functional tumours (NF). Data are expressed as mean+S.D. and a P value of <0.05 (unpaired t-testing) deemed significant.

Patients had a mean age 68 years, eight males. Four patients with functional tumours were identified based on the results of comprehensive endocrine investigations; two phaeochromocytomas and two adrenocortical carcinomas. The tumour hounsfield units and size were higher in these patients with functional tumours when compared to non-functional ones although not significantly so; size (F vs NF, 68.25+45.39 vs 23.76+8.022 mm, P=0.11), hounsfield units (F vs NF, 64.25+10.34 vs 38.29+31.47, P=0.13). There was a weak but positive relationship between size and hounsfield units with a correlation coefficient of 0.32. 24-h urine catecholamine and free cortisol were more commonly abnormal in these functional tumours.

Our study will suggest that adrenal tumour size of above 30 mm and a hounsfield unit of above 40 are predictive of functionality and only these should be subjected to extensive endocrine investigations. The lack of statistical significance could be due to the small sample size of our study and will indicate the need for larger studies to confirm our findings.