A case of adrenal oncocytoma: reviewing the literature of radiological finding

Oncocytoma is a tumour that predominantly occurs in the kidneys and salivary glands. Only approximately 200 cases have been reported to be of adrenal origin to date, and only a few reports about its radiological findings have been published so far. Herein, we present the CT and MRI findings of an adrenal oncocytoma observed in a patient suspected of having mitochondrial abnormalities, along with the pathological findings. The tumour was roughly classified into three areas: a hypercellular region, a region containing fibrous tissue, and an oedematous region. These corresponded to the restricted diffusion area on the apparent diffusion coefficient map, the gradually enhanced area at the secretory phase on contrast-enhanced CT scan, and the obvious hyperintensity on the T2-weighted image, respectively. We also discuss these findings in the context of previously reported radiological findings in the literature. Diagnosing adrenal oncocytoma through imaging is challenging, and it is crucial to consider the possibility of malignancy while making the differential diagnosis. Small-sized homogenous tumours may be hard to differentiate from lipid-poor adenomas, while larger inhomogeneous ones are hard to distinguish from adrenal cancer.