  Context. There exist few variability studies of stars in the region in the
Hertzsprung-Russell diagram between the A and B-star pulsational instability
strips. With the aid of the high precision continuous measurements of the CoRoT
space satellite, low amplitudes are more easily detected, making a study of
this neglected region worthwhile. Aims. We collected a small sample of B stars
observed by CoRoT to determine the origin of the different types of variability
observed. Methods. We combine literature photometry and spectroscopy to measure
the fundamental parameters of the stars in the sample, and compare
asteroseismic modelling of the light curves with (differentially rotating)
spotted star models. Results. We found strong evidence for the existence of
spots and differential rotation in HD 174648, and formulated hypotheses for
their origin. We show that the distinction between pulsations and rotational
modulation is difficult to make solely based on the light curve, especially in
slowly rotating stars.
