A surgeon operates on a patient with a pheochromocytoma involving the adrenal gland. He requests examination of intraoperative frozen sections by the pathology laboratory. Which of the following criteria can be used to determine if the lesion is benign or malignant?

Pheochromocytomas, and their related counterpas in extra-adrenal sites called paragangliomas, are notorious because the only reliable indicator of metastatic potential is the presence of distant metastases. Very malignant-appearing tumors may not metastasize and benign-appearing tumors may produce metastases. In practice, there is no way for the pathologist to make the decision on frozen (or permanent) section analysis unless metastasis has already occurred and can be documented. These tumors should all be considered "potentially malignant." Ref: Busaidy N.L., Habra M.A., Vassilopoulou-Sellin R. (2011). Chapter 38. Endocrine Malignancies. In H.M. Kantarjian, R.A. Wolff, C.A. Koller (Eds), The MD Anderson Manual of Medical Oncology, 2e.