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Adrenocortical oncocytomas are rare adrenal neoplasms and are most often reported as nonfunctioning adenomas. A minority, however, exhibit steroid hormone hypersecretion and may present with Cushing's syndrome, pheochromocytoma-like syndromes, feminization in males, or virilization in females. Adrenocortical oncocytoma presenting with primary aldosteronism is an exceptionally uncommon entity.Case presentation: We report a 44-year-old man with severe hypertension and hypokalaemia, accompanied by a right adrenal lesion on computed tomography. A comprehensive renin-angiotensin-aldosterone system evaluation and confirmatory testing supported primary aldosteronism. Adrenal venous sampling demonstrated right-sided aldosterone secretion dominance. The patient subsequently underwent laparoscopic right adrenalectomy. Postoperative histopathology identified an adrenocortical oncocytoma. Immunohistochemistry for aldosterone synthase (CYP11B2), together with biochemical findings and functional interpretation at the cellular level, supported the diagnosis of an aldosterone-secreting adrenocortical oncocytoma.

The patient achieved biochemical correction and clinical improvement, with favourable outcomes at 19-month follow-up. Although most oncocytomas behave benignly, this tumour type carries potential malignant risk. Once adrenocortical oncocytoma is diagnosed, surgical resection is recommended to reduce the risk of recurrence and metastasis.