Cindy was born at full term by caesarean section for a maternal history of previous uterine surgery. The antenatal history and ultrasound scan were unremarkable. She was born with a birth weight of 3.2 kg. We were consulted to assess Cindy, as a sacral dimple was noted after birth. Upon physical examination, Cindy’s body weight and height were at the 50th centile. Her head circumference was at the 75th centile. The neurological examination was normal. There was a left buttock mass, located 1 cm above the anal opening. It is soft in consistency and measured around 8 cm in diameter. The overlying skin was intact. There was a sacral dimple. The lower limbs examination showed normal muscle tone and reflexes, but there was a right postural clubfoot. The anal tone was not decreased. How would you proceed in evaluating and treating Cindy, a child who presents with a back mass at birth?