Fluorodeoxyglucose (FDG) Uptake in the Remnant Adrenal Gland Mimicking Tumor Recurrence in a Patient With Adrenocortical Carcinoma After Treatment With Mitotane.

Adrenocortical carcinoma (ACC) is a rare malignancy with poor prognosis. Its diagnosis requires clinical suspicion and confirmation through laboratory and imaging studies, including computed tomography (CT), magnetic resonance imaging (MRI), and abdominal ultrasound, as well as histological confirmation. Positron emission tomography (PET) is useful for distinguishing between benign and malignant lesions and for evaluating tumor recurrences or metastases. A case is described in which the uptake of fluorodeoxyglucose (18F-FDG) in a remnant adrenal gland could be misinterpreted as tumoral pathology. The article presents the case of a patient with ACC who, after treatment, showed increased FDG uptake in the remnant adrenal gland, which disappeared after discontinuation of treatment with mitotane. Possible explanations for this increase in FDG uptake are discussed, including the action of mitotane. In summary, it is highlighted that FDG uptake in remnant adrenal glands in patients treated with mitotane does not always indicate tumor recurrence or adrenal hypertrophy.