Atypical astrocytes and Rosenthal fibers in a case of amyotrophic lateral sclerosis associated with a cerebral glioblastoma multiforme.

A case of amyotrophic lateral sclerosis (ALS) and cerebral glioblastoma multiforme is presented in which bizarre astrocytes were found in the degenerating lateral corticospinal tracts, along with Rosenthal fibers, which were present in the corticospinal tracts of the lower medulla and spinal cord, and in anterior horns. These bizarre astrocytes did not result from direct infiltration of tumor from the cerebrum. "Malignant transformation" and/or an exceptionally intense glial response to the corticospinal tract degeneration are discussed as possibilities for the development of these bizarre astrocytes. Rosenthal fiber formation is described, to our knowledge, for the first time in ALS.