The injuries and the subsequent gangrene infection were so bad that one of his hands from the wrist down had to be amputated, and two fingers had to be removed from the other hand, plastic surgery professor at the hospital Dr Rakesh Kain said.
Gangrene develops when body tissues die due to loss of blood supply such as after tissues are damaged by fire.
"This procedure was challenging and required specialised anaesthesia to keep blood flow going for the survival of the toes, which were then fixed to the palm," Dr Kain told news agency PTI.
Some skin on the boy's hands was grafted from other parts of his body. The serious damage to the boy's hands left him incapable of even holding a pen and so he lost confidence to study, doctors said.
After the 10-hour-long surgery, doctors said normal blood circulation on the boy's hands has been restored and parts of his hands that got burnt in the fire will heal over time.
Dr Kain said the boy from Nepal will now be able to use his fingers and do routine work.
According to US-based medical non-profit group Mayo Clinic, chances of developing gangrene are higher if a person has an underlying condition that can damage blood vessels and affect blood flow, such as diabetes.
Gangrene is a serious condition and needs immediate treatment, doctors say. A condition called 'septic shock' can occur if bacterial infection that started in the damaged tissue spreads throughout the body.
(With inputs from PTI)