What other illnesses have similar symptoms to pheochromocytoma?

Many. Anxiety, panic attacks, essential hypertension, hyperthyroidism, illicit drug use, carcinoid syndrome, cardiac arrhythmias, menopause, preeclampsia - to name a few.
Diff Dx of Pheo. Anxiety and panic attacks, hyperthyroidism, use of illicit substances (drugs), carcinoid syndrome, cardiac arrhythmias, menopause, preeclampsia un controlled hypertension.