Adrenal myelolipoma (AML) is a rare, non-functioning, benign tumour1. 70% of AMLs are small. Very few are bilateral. Myelolipomas (≥6 cm) can cause mass effects, haemorrhagic changes and resection should be considered2.
A 56-year-old man was incidentally diagnosed with bilateral AMLs in 2017. The right-sided tumour measured 52 x 32 x 47 mm and left one was 42 x 30 x 35 mm with marked hypo-intensity -40 Hounsfield units3. He underwent active surveillance to avoid bilateral adrenalectomy. He was asymptomatic until the results of the most recent scan which showed a significant increase in size of right adrenal lesion. He subsequently noted bilateral flank pain over a few weeks. On examination, he was normotensive and clinical features did not suggest Cushing's syndrome. The adrenal lesions were not palpable.
Plasma metanephrines, renin to aldosterone ratio and DHEAS were normal, suggesting non-secreting tumours. There is a theory that elevated ACTH may drive the growth4, but ACTH was not raised. Addison's disease and congenital adrenal hyperplasia (CAH)5 were excluded. 1 mg dexamethasone suppression test excluded Cushing’s syndrome. Repeat CT in 2018 revealed an increase in size of right lesion with a stable left one. In 2021, the right-sided lesion further grew bigger 73 x 65 x 82mm, despite stable left mass (Figure 1).
There are no specific guidelines for management of AML and management is individualised. Given significant growth rate (maximum diameter up to 8.2 cm), it was decided at the endocrine radiology meeting that, it would be reasonable to remove right adrenal lesion with ongoing monitoring of left side radiologically. Risk of left adrenal haemorrhage is low. Currently, he is awaiting surgical review.
Figure 1: CT (Right to left) right adrenals: 52 x 32 x 47 mm (2017), 54 x 31 x 59 mm (2018), 73 x 65 x 82mm (2021).