Although Schwann cell-derived
tumors show typical histological features, the broad variety of spindle cell
tumors that exist can impede the diagnostic procedure. In this study, we present
aldehyde dehydrogenase 1 (ALDH1) as a new, viable diagnostic marker for Schwann cell
tumors.
Protein expression was examined by immunohistochemistry in
schwannomas,
neurofibromas, and
malignant peripheral nerve sheath tumors (
MPNST) as well as in non-neoplastic peripheral nerve sheath specimens.
Meningiomas and other spindle cell-like
tumors served as control tissue. ALDH1 immunohistochemistry was performed on human FFPE samples. Staining evaluation was performed according to a defined immunoreactive score. All
schwannomas and
neurofibromas were strongly positive for ALDH1.
MPNST were positive too, but with a clear reduction of ALDH1 expression. All non-Schwann-cell-derived
tumors showed no immunoreaction. This leads to the conclusion that ALDH1 can serve a as viable diagnostic marker for
schwannomas and
neurofibromas as it was expressed and detected by IHC in all samples. Furthermore, ALDH1 expression seems to be a sign for differentiation as it diminishes during malignization of Schwann cell
tumors. Hence, its expression level provides information about the biological behavior of the
tumor.