  We present 4-micron ISAAC imaging and spectroscopy of the extremely
metal-poor dwarf galaxy SBS 0335-052, aimed at a better understanding of the
dust in this low-metallicity galaxy. The 4-micron emission turns out to be very
compact, confined to the brightest pair of Super Star Clusters (SSCs). The
Ks-L$^\prime$ color is extremely red, and the $L^\prime$ emission is consistent
with the extrapolation of the ISO mid-infrared spectral energy distribution
(SED). From hydrogen recombination lines and a fit to the near-/mid-infrared
SED, we confirm a visual extinction of >= 15 mag. Our data suggest that the
sites of the optical and infrared emission are distinct: the optical spectral
lines come from an almost dustless region with a high star formation rate and a
few thousand OB stars. This region lies along the line-of-sight to a very dusty
central star cluster in which there are more than three times as many massive
stars, completely hidden in the optical. From the extinction, we derive an
upper limit for the dust mass of 10^5 M$_\odot$ which could be produced by
recent supernovae.
