Endocrine Abstracts

A 77 year old gentleman was referred to the endocrinology team following the incidental finding of an adrenal nodule on computer tomography (CT) colonography. Following this, dedicated CT of the adrenal showed a 4cm nodule with an attenuation of 30 Hounsfield Units. Biochemical investigation found no evidence of adrenal insufficiency or functional hormone production. Subsequent imaging by magnetic resonance imaging (MRI) and further CT showed stable appearances in size of the lesion, however concern remained regarding the risk of malignancy. Fluorodeoxyglucose-positron emission tomography was then performed, and this found moderate to intense activity in the area. The patient underwent adrenalectomy. Histopathology of the adrenal mass showed necrotising granulomatous inflammation, raising suspicion of adrenal tuberculosis (TB) and although acid-fast bacilli were not isolated on culture, TB ELISpot was positive. Differential diagnoses included sarcoid and granulomatosis with polyangiitis. The latter was considered unlikely given the clinical history and serum angiotensin-converting enzyme levels were not elevated. Multidisciplinary discussion decided this was likely a case of latent TB. Systemic anti-TB treatment was not initiated due to absence of symptoms and lack of evidence to suggest TB at other body sites. Less than 2% of adrenal incidentalomas are due to isolated adrenal TB¹. TB is the most common cause of primary adrenocortical insufficiency caused by infection². Adrenal tuberculosis is thought to rarely mimic non-functioning adrenal incidentaloma. Future development of imaging techniques and frequency of imaging will likely increase detection of non-functioning incidentalomas. This case suggests the importance of considering TB as a differential diagnosis whilst investigating non-functioning adrenal incidentalomas.

References

1. Kelestimur F. The endocrinology of adrenal tuberculosis: the effects of tuberculosis on the hypothalamo-pituitary-adrenal axis and adrenocortical function. Journal of Endocrinological Investigation, 27(4) ( 2004) 380–386. doi: 10.1007/BF03351067.

2. Bouknani, N. et al. Bilateral adrenal tuberculosis: about a case. The Pan African Medical Journal, 29 (2018) 212. doi: 10.11604/pamj.2018.29.212.15459.

3. Lee, JM. et al. Clinical Guidelines for the Management of Adrenal Incidentaloma. Endocrinology and Metabolism (Seoul, Korea), 32(2) (2017) 200–218. doi: 10.3803/EnM.2017.32.2.200.