This paper introduces a novel distributed topology management scheme for 5G ultra-small cell networks (SCNs). The scheme is designed to switch as many base stations as possible to sleep mode without significantly degrading the Quality of Service (QoS). This is fulfilled through traffic perception by each base station in its dynamically changing monitoring area. Simulation results show that the proposed adaptive scheme is able to enhance the network stability and significantly improve energy saving for various traffic density levels while maintaining a good QoS. It is evident that the scheme can sustain at least 1 Gbps/km²/MHz traffic, and consume 40% less power at low traffic loads than with no topology management and consume 16% less power compared to the best static scheme in which each base station adopts traffic perception in a fixed monitoring area. The reasons for these merits are explained and the impact of varying the critical scheme parameters is analyzed.