Answer: Myxoid variant of adrenal cortical adenoma

Histology: The tumor is well-circumscribed without any obvious mitoses or areas of necrosis. The nuclei are bland without atypia. The most prominent finding is the myxoid change within the tumor.

Discussion: The presence of myxoid changes in adrenal cortical neoplasms may complicate their diagnosis and raise the possibility of malignancy of metastatic origin. However, myxoid variants of adrenal cortical adenoma have been described and should be considered in the differential diagnosis of such lesions.

Brown et al (1) studied the histopathologic features of 14 cases of myxoid adrenocortical neoplasms, including six adenomas and eight carcinomas. All patients with adenomas with sufficient follow-up were alive with no evidence of recurrence or metastatic disease. Histologically, areas of myxoid change can be focal or extensively involve the entire tumor. The myxoid foci stain positively with Alcian blue but usually are negative with PAS and mucicarmine. Myxoid adrenocortical neoplasms share the same immunophenotype with their non-myxoid counterpart (vimentin +, synaptophysin +, and alpha-inhibin +).

Clinical and histopathologic features used to differentiate usual adrenocortical carcinomas from adenomas should also be used in myxoid cortical neoplasms. Albeit a rare occurrence, myxoid adrenal cortical neoplasms should be included in the differential diagnosis of myxoid retroperitoneal neoplasms.

Reference(s):
– Brown FM, Gaffey TA, Wold LE, Lloyd RV. Myxoid neoplasms of the adrenal cortex: a rare histologic variant. Am J Surg Pathol. 2000 Mar;24(3):396-401.