Adrenocortical carcinoma (ACC) is a rare endocrine malignancy with an annual incidence of approximately 0.7–2 cases per million population. Oncocytic adrenocortical carcinoma is an exceptionally uncommon histological variant characterized by abundant eosinophilic, mitochondria-rich cytoplasm and unpredictable biological behavior. We report the case of a young male who presented with rapidly progressive metastatic ACC with oncocytic features. The patient presented with abdominal symptoms and was found to have a large adrenal mass on imaging. Further evaluation demonstrated advanced disease with distant metastatic involvement. Histopathological examination revealed an oncocytic neoplasm of adrenal cortical origin with malignant features consistent with oncocytic ACC. Despite multidisciplinary management and oncological evaluation, the disease exhibited aggressive progression over a short period. The patient’s clinical course highlighted the challenges associated with early diagnosis, prognostication, and therapeutic decision-making in this rare tumour subtype. Oncocytic ACC poses significant diagnostic difficulties due to its rarity and overlapping radiological and pathological features with other adrenal neoplasms. Although the Lin-Weiss-Bisceglia criteria assist in distinguishing benign from malignant oncocytic adrenal tumours, predicting clinical behaviour remains challenging. Metastatic disease at presentation is associated with a poor prognosis and limited treatment options. Surgical resection remains the cornerstone of management when feasible, while systemic therapies including mitotane and combination chemotherapy may be considered in advanced disease. This case emphasizes the importance of maintaining a high index of suspicion for adrenal malignancy in young patients presenting with large adrenal masses and demonstrates the aggressive nature of metastatic oncocytic ACC. Increased reporting of such rare cases is essential to improve understanding of prognostic factors and guide future therapeutic strategies.

Sultana Jannatun Nahar is a Trust Grade CT2 Doctor in Acute Medicine at United Lincolnshire Teaching Hospitals NHS Trust, UK. She has a strong interest in clinical research, particularly in endocrinology, oncology and acute medicine. She has authored and co-authored several peer-reviewed case reports published in international journals and has presented her work at national and international scientific conferences.