Adrenal collision tumour comprised of adrenocortical carcinoma and myelolipoma in a patient with congenital adrenal hyperplasia

Adrenal myelolipoma is a benign tumour characterized by the presence of macroscopic fat. Further workup is not necessary if a diagnosis of adrenal myelolipoma is obtained via imaging. We report the first case of adrenal collision tumour comprised of adrenocortical carcinoma and myelolipoma in a patient with bilateral myelolipomas and congenital adrenal hyperplasia. Computed tomography showed a large right adrenal mass consisting of two different components: soft tissue with peripheral heterogeneous enhancement and macroscopic fat. Imaging findings reflected features of both adrenocortical carcinoma and myelolipoma. Although this entity is rare, collision tumour containing an adrenocortical carcinoma component should be suspected if portions of an adrenal mass partially consist of peripheral heterogeneous enhancement.