An 85-year-old man was electively admitted to hospital for a coronary angiogram and detected with hypokalaemia which ultimately led to a diagnosis of metastatic adrenocortical carcinoma (ACC). Given persistent hypokalaemia despite treatment with potassium supplementation he underwent screening for hyperaldosteronism and hypercortisolism even though he was not Cushingoid in appearance. There was no evidence of hyperaldosteronism, but the biochemical screen was consistent with ACTH independent hypercortisolism evident in serum, urine and saliva, prompting CT adrenal imaging which identified a 33mm left adrenal mass. The CT scan also identified several small pulmonary and liver lesions potentially consistent with a metastatic malignancy but not amenable to biopsy due to their small size and location. Subsequent PET imaging confirmed FDG avidity with two small pulmonary lesions, one small liver lesion, gastric and left adrenal gland uptake with a differential diagnosis of lung, stomach or adrenal cancer. Biopsy was avoided due to risk of tumour seeding and a posterior retroperitoneoscopic left adrenalectomy was recommended for tissue diagnosis and potential steroid hormone control. The adrenal histology was consistent with a primary ACC but glucocorticoid excess persisted necessitating adrenal blockade with ketoconazole post-operatively. Unfortunately, due to persistent hypercortisolism in the setting of metastatic ACC he rapidly became frail rendering him unsuitable for systemic chemotherapy and mitotane. He died within three months of presentations.
The case highlighted ACC as rare cause of hypokalaemia, the need for adrenalectomy in some instances to obtain a tissue diagnosis and the lack of efficacy of adrenalectomy for biochemical control with metastatic ACC.