Solar radio spikes and quasi-periodic pulsations (QPPs) can occur as fine structures in dynamic radio spectra. While their physical interpretation is still under debate, they are seen to contain detailed information about the complex energy release processes in solar flares. In this paper we investigate the relation of both phenomena in a case study of a M-class flare event on 21 June 2015. The imaging-spectroscopic analysis is based on observations by the Mingantu Spectral Radioheliograph (MUSER) and compared with EUV observation by the Atmospheric Imaging Assembly (AIA). The location of microwave (0.4–2 GHz) sources with respect to the flaring active region is discussed for selected times. Each group of spikes occurred simultaneously with quasi-periodic pulsations (QPPs). The spatially resolved data shows that during the flare process the radio sources were mainly located in the eastern bipolar region. For three groups of peculiar fine structures, we find that (1) the FS radio sources are mainly in the fan area converged to western spot instead of the eastern bipolar region; (2) the FS radio sources are in both the eastern bipolar region and the fan area; (3) the FS radio sources are mainly in the eastern bipolar region. This may be due to the interactions between the shearing flare loops in the eastern bipolar region and the fan area converged to the western sunspot.