Aperio SVS (or Aperio SVS TIFF, or SVS) is a graphics format associated with Aperio microsocope scanners, and other products. It is a subformat and extension of TIFF.
There isn't necessarily any reliable way to distinguish SVS files from other TIFF files. For SVS, the "ImageDescription" TIFF tag probably contains the string "Aperio", and may have extra metadata stuffed into it. If the compression type is 33003 or 33005, it's probably SVS.