O-07 Cortisol-Secreting Oncocytic Adrenocortical Neoplasm Presenting With Hypertension and Hypokalaemia

Abstract Introduction Oncocytic adrenocortical neoplasms (OANs) are rare. They are usually asymptomatic, benign and non-functional. Histologically, they display large polygonal cells with granular and eosinophilic cytoplasm. We report a case of left benign cortisol-secreting OAN with initial presentation of hypertension and hypokalaemia. Clinical Case A 46-year-old Asian female with a 10-year history of hypertension and hypokalemia was referred to our clinic for evaluation. She was taking potassium supplement and multiple anti-hypertensives. On physical examination, blood pressure was 141/69 mmHg, BMI 30.9 kg/m². She had facial plethora. There were no abdominal striae, easy bruising, or proximal myopathy. Her serum potassium level was 2.8 mmol/L (3.5-4.5), am cortisol 221 nmol/L (101-536), aldosterone/renin ratio 77 ( 550). Laboratory parameters are summarized in Table 1. A CT urogram was later done during an admission for pyelonephritis, revealing a 2.8 cm left adrenal nodule over lateral limb (Figure 1). The pre-contrast attenuation was 20 Hounsfield units (HU). There were no macroscopic fat or calcifications. Hormonal studies revealed normal 24-hour urine free metanephrines (Table 2). Her ACTH level was 1.7 pmol/L (10). Both 1mg overnight and low dose dexamethasone suppression tests were non-suppressible, cortisol 126 and 93 nmol/L (50) respectively. She was diagnosed with left adrenal Cushing’s. Associated metabolic complications included diabetes, hypertension and hyperlipidaemia. Laparoscopic left adrenalectomy resected a 2.5cm left adrenal adenoma. Macroscopically, it was a well-defined and roundish tumour with yellowish cut surface, weighing 52 grams. Microscopically, it was formed by clusters and nests of polygonal cells. Tumour cells exhibited abundant granular eosinophilic nuclei and cytoplasm. There were no coagulate tumour cell necrosis, mitotic figures or evidence of lymphovascular invasion. Immunostaining was positive for Neuron-specific enolase, synaptophysin, alpha-inhibin, SF-1 and S-100; negative for ACTH, EMA, Cam4, Melan-A, HMB45 and chromogranin. The morphology of tumour cells was suggestive of an OAN. There was no morphologic evidence of aggressive clinical behaviour according to the Modified Weiss system. Potassium supplement was weaned off after surgery. An interval CT scan 2 years later showed no recurrence. Conclusion Cortisol-secreting OANs are uncommon, with less than 40 cases reported in the literature. They can present with hypertension and hypokalaemia. Diagnosis is made after surgical resection by histology, and its malignant potential can be classified by the Modified Weiss system. These tumours should be monitored with serial imaging as they may recur, although there are no guidelines on the surveillance schedule.Figure 1:CT Urogram showing a left 2.8cm adrenal nodule over lateral limb, pre-contrast 20 HU, no macroscopic fat or calcifications Table 1:Patient's blood parameters Table 2:Patient's 24-hour urine free metanephrines