I have a tiny white patch on my thigh since childhood. this light spot remains the same size over the years and is not scaly. is it tinea versicolor?

Birth mark: What you described is likely an under-pigmented area that is otherwise normal. You may leave it alone. For good health - Have a diet rich in fresh vegetables, fruits, whole grains, milk and milk products, nuts, beans, legumes, lentils and small amounts of lean meats. Avoid saturated fats. Drink enough water daily, so that your urine is mostly colorless. Exercise at least 150 minutes/week and increase the intensity of exercise gradually. Do not use tobacco, alcohol, weed or street drugs in any form. Practice safe sex, if you have sex.

Ash leaf spot: Tinea versicolor comes and goes and is widely distributed. Most often these are "ash leaf" spots, especially if the long axis is parallel the dermatomes. If you had six, and were otherwise affected with a variety of tumors and nodules, I'd suspect tuberous sclerosis. One ash leaf spot means nothing whatever -- several percent of folks have one.