Thane: Doctors at Kalwa's civic run Chhatrapati Shivaji Maharaj Hospital performed a two-hour long surgery on Wednesday on a 15-year-old girl and removed a hair ball weighing 2.5 kg from her stomach, a doctor said.

"She is a mentally retarded girl with a long standing habit of eating of her own hair and rough paper. She was brought for loss of appetite, loss of weight and abdominal distension," Sukesh Thakur, a member of the three-member team of doctorsm including Vishwas Sapatnekar and Anupama Takawale, who performed the surgery said.