Some cannot be removed; they are too close to vital organs or actually inside them, Soltoski said.
The boy's mother, a maid, brought him to a hospital in the small northeastern city of Ibotirama on Thursday, saying he was complaining of pain. Three days later, after X-rays revealed some of the needles, doctors had him shifted to a larger hospital in Barreiras.
The mother told police she doesn't know how the needles got inside her son, but police have opened an investigation. The boy's name was withheld because of his age.
The boy's father, Gessivaldo Alves, told Brazil's A Tarde newspaper that he believes his son could have been a victim of a black magic ritual. Alves said he visited the home where the boy was living with his mother and stepfather and found unspecified items that could be used for black magic, A Tarde reported.
The police inspector in charge of the case, Helder Fernandes Santana, told Brazil's O Globo newspaper that is was no doubt someone stuck the needles into the boy, but said he had no suspect and did not disclose a motive.
"It's clear someone inserted the needles, that's for sure," he said in comments published Wednesday. "We still don't know who did this."
Santana did not immediately return telephone messages Wednesday seeking comment.
Soltoski said he believes the needles were stuck into the child's body one by one because it would have been impossible for him to swallow them.
"We think it could have only been by penetration because we found needles in the lung, the left leg and in different parts of the thorax. It couldn't have been by ingestion," Soltoski said.
Doctors found no signs of outside wounds on the boy, but X-ray images carried by Brazilian Web sites clearly showed some of the needles inside his body.
The boy is in intensive care, but Soltoski said his condition has improved since he was admitted.