Giant nonfunctioning carcinoma of the adrenal cortex mimicking renal cell carcinoma: a diagnostic dilemma

Adrenocortical carcinoma is a rare, highly malignant neoplasm that originates in the adrenal cortex and is difficult to differentiate from renal cell carcinoma, especially if it is gigantic and nonfunctional. We report the case of a 40-year-old man with an incidental mass in the right upper abdomen. Magnetic resonance imaging revealed that the mass originated from the right kidney and was highly suggestive of renal cell carcinoma. However, histologic examination after radical nephrectomy confirmed the mass to be an adrenocortical carcinoma compressing the kidney. We discuss the obscurity and implications of such a diagnosis.