Myles Bradbury has lodged an appeal against a 22-year jail sentence imposed last December.
He admitted abusing 18 children at Addenbrooke's in Cambridge between 2009 and 2013.
The mother of the 11-year-old abused when he was kept on as a patient told the BBC Bradbury should never be freed.
Bradbury, 41, from Herringswell in Suffolk, was jailed at Cambridge Crown Court for sexual assault, voyeurism and possessing more than 16,000 indecent images.
The court heard the images of his victims were taken in the hospital.
Victims told investigators Bradbury had focused on examining their private parts when there was no medical need to do so.
The child, who is now 13, was referred to Bradbury because his older sister had a blood disorder and it was feared he might have the same condition.
But, his mother said, there was nothing wrong with him.
Instead of discharging him from his patient list, Bradbury continued seeing and abusing the boy for a year.
The boy is currently on heavy medication to deal with the mental effects of his abuse.
His mother said she did not know how Bradbury could appeal.
She said: "He is in prison now, probably doing his crafts or whatever. We are suffering every day.
"He does not understand the knock-on effect he has had on families."
Bradbury's appeal will be heard at the Royal Courts of Justice on 12 June.
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