Basketball Hall of Fame inductee Dikembe Mutombo is having treatment for a brain tumor, the NBA said on Saturday.
The former center played 18 seasons in the NBA with six teams, gaining a reputation as one of the league's greatest shot blockers which earned him the Defensive Player of the Year award four times in his career.
Mutombo's prime years were spent with the Denver Nuggets, who drafted him in 1991, and Atlanta Hawks - with both teams retiring his number 55 jersey. He also played for Philadelphia 76ers, New Jersey Nets, New York Knicks and Houston Rockets.
"Dikembe Mutombo is currently undergoing treatment for a brain tumor. He is receiving the best care possible from a collaborative team of specialists in Atlanta and is in great spirits as he begins treatment," the NBA said in a statement.
"Dikembe and his family ask for privacy during this time so they can focus on his care. They are grateful for your prayers and good wishes."
The 56-year-old, who stands 7 feet 2 inches tall, was an eight-times All-Star and is second on the all-time list of career blocks. His iconic finger wag after a successful block has been copied by several players.
He is also famous for his humanitarian work, becoming the first person to receive the NBA's humanitarian award twice, mainly through his work with the Dikembe Mutombo Foundation.
Established in his native Democratic Republic of Congo in 1997 to raise finds for charity, it led to a $29 million, 300-bed hospital dedicated to fighting malaria.