Case Report: Low-dose mitotane in a case of recurrent adrenocortical carcinoma: a 20-year clinical perspective.

Adrenocortical carcinoma (ACC) is a rare malignancy with a high risk of recurrence, and the prolonged use of mitotane is often limited by its narrow therapeutic window and endocrine and gastrointestinal toxicity. We describe a woman who presented at 42 years of age with a right adrenal mass in 2000. The tumour was macroscopically removed in 2001 and was diagnosed as a 7.4 × 5.6 × 6.0 cm, partially necrotic ACC with focal calcifications, invasion of the surrounding adipose tissue, and microscopically involved margins (pT3N0M0). A local recurrence was resected in 2006, after which mitotane was initiated at 6 g/day. Gastrointestinal intolerance required reduction to 3 g/day and subsequently to 1-2 g/day, with a temporary interruption in 2009. A contralateral adrenal lesion was removed in 2011 and proved to be an adenoma, resulting in bilateral adrenalectomy and lifelong glucocorticoid and mineralocorticoid replacement. Mitotane concentrations remained subtherapeutic for many years but reached 16.9 mg/L in 2021 and 20.3 mg/L in 2022 on 2 g/day. Mitotane was discontinued on 5 June 2025 after approximately 19 years of treatment. At the latest assessment, the patient remained in good general condition and continued hydrocortisone 40 mg/day, fludrocortisone 0.1 mg/day, and levothyroxine. Contrast-enhanced computed tomography on 28 May 2026 showed no local recurrence or metastatic disease. This case documents sustained disease control during and after almost 20 years of individualized mitotane therapy following recurrent ACC. It emphasizes the importance of dose adaptation, therapeutic drug monitoring, careful endocrine replacement, and cautious interpretation of long-term benefit in a single patient.