Myxoid adrenocortical carcinoma: a clinicopathologic and immunohistochemical study of 7 cases, including 1 case with lipomatous metaplasia.

Adrenocortical carcinomas (ACCs) with myxoid features are rare neoplasms. We identified 7 cases of myxoid ACC and studied the clinicopathologic and immunohistochemical features of these neoplasms. The patients were 5 men and 2 women with a mean age of 45 years. Histologically, the tumors contained alcian blue-positive myxoid areas ranging from 10% to 50% of the tissue examined. One case showed lipomatous metaplasia. Areas of conventional ACC were present in all cases. Immunohistochemically, the tumors were positive for steroid receptor cofactor 1, inhibin, melan A, calretinin, and synaptophysin but negative for high-molecular-weight cytokeratin, CAM5.2, and Pax8. Clinical follow-up information for 4 patients demonstrated that all patients had died of their disease 11 to 69 months after diagnosis. Myxoid ACCs are rare tumors that expand the differential diagnosis of myxoid neoplasms involving the retroperitoneum. Contrary to previous reports proposing that the biologic behavior is similar to conventional ACC, our series seems to indicate that myxoid morphology is associated with more aggressive behavior.