How do you diagnose adrenal cortical cancer?

Scan and biopsy. By blood tests measuring levles of adrenal hormones, by ct scan and biopsy.
Avoid biopsy. Actually, we avoid preoperative biopsy of adrenal masses before surgery (unless we are suspecting metastatic cancer from the lung, etc. If an adrenal carcinoma is large enough, the ct findings are usually obvious. For indeterminate adrenal masses greater than about 5 cm, we recommend laparoscopic adrenalectomy (after excluding excess hormone production). Needle bx in this situation is not accurate.