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Percutaneous microwave ablation of adrenal remnant tissue. A novel treatment modality for persistent Cushing’s disease

R Ramli, S Hameed, F Wernig, A Sam, E Leen, F Palazzo, N Mendoza, E Hatfield, N Martin, K Meeran, Imperial Healthcare NHS Trust

A 29-year-old lady presented with features of Cushing’s syndrome in October 2014. Investigations confirmed ACTH–dependent Cushing’s syndrome. An MRI scan showed a 4.5 mm right-sided pituitary lesion and subsequent inferior petrosal sinus sampling confirmed a central source of ACTH hypersecretion. She underwent trans-sphenoidal pituitary surgery in January 2015. Histology confirmed a corticotroph adenoma with a Ki-67 proliferation index of 1%. However, a mean cortisol of 298 nmol/L on a cortisol day curve was highly suggestive of persistent hypercortisolaemia. MRI scanning confirmed small-volume residual tumour in the right anterior sella. She remained symptomatic and underwent a second trans-sphenoidal pituitary surgery in April 2015. Histology from this surgery showed normal adenohypophysis only. The second surgery was complicated with a post-operative CSF leak and meningitis. A cortisol day curve 6 weeks later showed a mean cortisol level of 474 nmol/L and further biochemistry investigations confirmed persistent hypercortisolaemia. Following MDT discussions, the patient underwent bilateral adrenalectomy in March 2016, with some difficulty encountered during removal of the left adrenal gland. As expected, histology of both adrenals showed evidence of adrenal hyperplasia. She was commenced on Prednisolone and Fludrocortisone postoperatively.

She continued to have difficulty losing weight 5 months post-adrenalectomy. An overnight dexamethasone suppression test confirmed persistent Cushing’s disease (9 am cortisol 383 nmol/L). Prednisolone was discontinued and she was commenced on Metyrapone. MRI Pituitary showed a right-sided pituitary adenoma extending between the intra- and supracavernous internal carotid artery segments. A Ga68 DOTATATE whole body PET CT showed appearance consistent with residual hyperplastic adrenal tissue in the left suprarenal region. She was discussed in the ICHNT Pituitary and Adrenal MDT meetings where percutaneous ablative approach of the residual adrenal tissue was considered the best management option due to the risks associated with further pituitary surgery or pituitary radiotherapy, or repeat abdominal surgery. Microwave ablation therapy was chosen as recent studies suggested similar or even superior efficacy when compared to radiofrequency ablation¹. She underwent CT-guided microwave ablation of the left adrenal remnant (120W) in July 2017, following which she was re-started on Prednisolone. Following the procedure, she improved significantly both clinically and biochemically. This case illustrates that percutaneous ablative approach of adrenal remnant tissue and possibly entire adrenal glands should be considered in the treatment of challenging Cushing’s disease.

References:

Venkatesan AM, Locklin J, Dupuy DE, Wood BJ. Percutaneous Ablation of Adrenal Tumors. Tech Vasc Interv Radiol. 2010 Jun; 13(2): 89-99.