Adrenocortical blastoma.

We report a previously undescribed virilizing malignant adrenocortical tumor in an 21-month-old infant with elevated serum alphafetoprotein. The tumor consists of a peculiar mixture of immature epithelial and mesenchymal elements as well as slit-like spaces partially lined by primitive epithelial cells. Focally, the tumor has features reminiscent of the normal embryologic development of the adrenal cortex. A panel of immunohistochemical stains revealed only vimentin reactivity. We propose the term "adrenocortical blastoma" for this unusual neoplasm.