Adrenocortical Carcinoma and Inferior Vena Cava Thrombosis: Diagnosis and Perioperative Management.

Adrenocortical carcinoma (ACC) is an endocrine malignancy with a poor prognosis due to its advanced stage at diagnosis and early metastatic potential. Misclassification is common when tumors arise near the renal-adrenal interface, particularly in cases with vascular invasion. We describe the case of a patient with a large retroperitoneal mass extending into the inferior vena cava whose initial imaging suggested a renal origin, resulting in deferred hormonal evaluation. Postoperative pathology confirmed ACC, and subsequent endocrine testing was consistent with a nonfunctional tumor. This case reinforces the need for improved guidelines and increased education, accounting for the variable presentations of ACC, to enhance diagnostic accuracy and optimize pre- and perioperative planning. As such, in cases of patients presenting with masses in the adrenal-adjacent regions, an endocrine workup of cortisol, androgens/estrogens, and mineralocorticoids should be the standard of care to rule out aggressive tumors such as ACC.