Adrenal cortical carcinoma with adenosquamous differentiation. Report of a case with immunohistochemical and ultrastructural studies.

We report the case of an adrenal cortical carcinoma with glandular and squamous differentiation, demonstrated by light and electron microscopy as well as by immunohistochemical studies. The patient was a 63-year-old man presenting with a large adrenal mass and markedly increased 24-hour urine metanephrine, initially suggesting the diagnosis of pheochromocytoma. Upon histological examination of the surgically excised tumor, the presence of adenosquamous differentiation was most consistent with a metastasis to the adrenal gland. No other primary tumor was later found at autopsy, however. It thus becomes evident with this case that squamous and glandular differentiation can be observed in primary adrenocortical carcinomas, and therefore the conventional approach to the immunohistochemical and ultrastructural features of these tumors is challenged. This type of aberrant morphology in adrenocortical carcinomas makes the differentiation from a metastatic carcinoma particularly difficult for the surgical pathologist. Clinical correlation is absolutely necessary for an accurate diagnosis, and occasionally, as was the case with this patient, only with postmortem studies can another primary be ruled out with certainty.