Thanks for the interesting question. It is difficult to tell for sure the cause without seeing the palms.
Some commoner causes of yellowish or orangy palms include excessive intake of beta carotene found in foods like carrots and spinich or lycopene, found in tomatoes and beets. In fact, my son has yellowish palms from eating lots of carrots! By cutting down on these foods, the orange hue should resolve.
Thyroid abnormalities and diabetes may also be possible causes. Contact with orange coloured dyes can also leave an orangu stain.
Sometimes, a localized area of thickening of the skin of the palms can give the palm an orangy appearance too.
If you are still unsure of the cause, you can see your doctor/dermatologist to confirm the diagnosis.
