Oncocytic Carcinoma: A Rare Hormone-Producing Tumor.

Oncocytic adrenocortical carcinoma (OACC) is a rare type of malignancy that affects the adrenal cortex. We describe the case of a 68‑year‑old woman with months of refractory hypertension, hypokalemia, headaches, night sweats, and palpitations. Computed tomography revealed a 113 mm left adrenal mass displacing the pancreatic tail and spleen. After a multidisciplinary review, she underwent open adrenalectomy. The 355 g tumor was well circumscribed; histology showed abundant eosinophilic oncocytes arranged in nests and trabeculae, 36 mitoses per 50 high‑power fields (including atypical figures), necrosis, and venous invasion, and the Ki‑67 index was 10%. These findings satisfied major and minor Lin-Weiss-Bisceglia criteria, confirming OACC. Immunohistochemistry was positive for calretinin, Melan‑A, synaptophysin, and inhibin, consistent with adrenocortical origin. Postoperatively, hypertension and potassium levels normalized with reduced antihypertensive therapy; she commenced steroid replacement and adjuvant mitotane. At early follow‑up, she remained clinically stable and disease‑free. This case highlights the importance of considering OACC in patients with large adrenal masses and resistant hypertension, demonstrates the value of multidisciplinary management and definitive surgery, and contributes to the limited evidence guiding adjuvant therapy for this uncommon tumor.