There is so much for us to learn in the story of the ten lepers. Watch this:
And it came to pass, as he went to Jerusalem, that he passed through the midst of Samaria and Galilee. And as he entered into a certain village, there met him ten men that were lepers, which stood afar off:

And they lifted up their voices, and said, "Jesus, Master, have mercy on us". And when he saw them, he said unto them, "Go show yourselves unto the priests." And it came to pass, that, as they went, they were cleansed.
(Luke 17:11-14)
They shouted to Jesus, "Master, have mercy on us." And Jesus cleansed them all.
And one of them, when he saw that he was healed, turned back, and with a loud voice glorified God, And fell down on his face at his feet, giving him thanks: and he was a Samaritan.

And Jesus answering said, "Were there not ten cleansed? But where are the nine? There are not found that returned to give glory to God, save this stranger." And he said unto him, "Arise, go thy way: thy faith hath made thee whole."
(Luke 17:15-19)
Notice that all ten were cleansed but only one was made completely whole. Which one? The one who returned to give thanks.

Noah Webster's 1828 Dictionary defines the word whole as: all, total, containing the total amount or number, the entire thing, complete, not defective or imperfect, unimpaired, unbroken; uninjured; sound; not hurt or sick; restored to health and soundness.

In other words, although the nine were cleansed and leprosy stopped eating away their flesh, they still had the signs that they once had the disease.

They may have had a limb missing or part of their face had been eaten away, and it remained that way.

But for the one who was made whole, he had no signs that he had ever had the disease. His body was completely restored.

Source: The Intensity of Your Desires by Carolyn Savelle
Excerpt permission granted by Jerry Savelle Publications