Truly mixed corticomedullary tumors (MCMTs) are extremely rare and present as a single tumor mass composed of an intimately admixed population of both adrenal cortical cells and pheochromocytes. The current study describes the first case of a mixed corticomedullary adrenal carcinoma. In addition, we also review the published data on MCMTs to determine their clinical features, biochemical characteristics, pathological findings, and management. In order to compose this review, a search of the international literature for MCMTs was conducted. Fifteen related articles were found. The clinical and pathological information was obtained for all reported cases. MCMTs were found almost exclusively in females. In the vast majority of patients, the symptoms were related to the tumor's hormone hypersecretion. Hypertension and diabetes were present in 80 and 40 % of cases, respectively. Cushing's syndrome was reported in eight cases (53.33 %). A final diagnosis was made in all cases after surgery based on the pathological results. As of the writing of this article, all published cases of MCMTs had benign clinical behavior, with no instances of metastasis or death due to the tumor. MCMTs are currently considered to be benign tumors. Ours is the first case of malignant MCMT reported in the literature. The potential for malignancy should therefore be considered for these tumors.