A RETROSPECTIVE REVIEW OF ADRENAL INCIDENTALOMAS IN MALAYSIA

CLINICAL CHARACTERISTICS AND NATURAL HISTORY

Abstract

INTRODUCTION/BACKGROUND
Adrenal incidentalomas (AI) are frequently detected during imaging for unrelated conditions, with the majority being benign and non-functional. Numerous studies on AIs have been conducted in the Western countries but there is a lack of data from this region.

METHODOLOGY
This retrospective study aimed to describe the clinical and radiological characteristics, as well as the natural history of AIs in a Malaysian cohort. Medical records of 251 AI patients from three tertiary hospitals were reviewed. Baseline demographic data, imaging characteristics, hormonal evaluations and histopathological findings were collected. Follow-up data on serial imaging, hormonal re-evaluations and eventual outcome were captured.

RESULT
The median age of the cohort was 58 years, with almost equal gender distribution and most tumors being non-malignant (92%) and non-functioning (72%).

Bilateral AIs were present in 24 (9.6%) patients. Ten were functioning with mild autonomous cortisol secretion (MACS) being the commonest subtype (80%).

Among the non-malignant AIs, 27% were functioning. Of these, the majority (51%) were diagnosed with MACS, followed by pheochromocytoma (27%), primary hyperaldosteronism (21%), and one case of overt Cushing’s syndrome. Functioning AIs were associated with higher rates of hypertension and osteoporosis, larger tumour size, greater tumour density, and a lower rate of absolute contrast washout.

Adrenalectomy was performed more frequently in the functioning group, primarily for MACS and pheochromocytoma. The majority (94%) of non-functioning benign AIs were managed conservatively. No malignant transformation was observed, and only one case became functional over a median follow-up of 30 months.

Of the 20 malignant AIs, 12 were primary adrenal cancers. The malignant AIs were more likely to present with weight loss, overt Cushing’s, larger tumor size, higher density, reduced contrast washout, and significantly higher mortality compared to non-malignant AIs.

CONCLUSION
This study suggests that most benign non-functioning AIs pose minimal risk of progression, supporting reduced follow-up in stable cases.