Immunocytochemical and ultrastructural study of Lewy body-like hyaline inclusions in familial amyotrophic lateral sclerosis.

Lewy body-like hyaline inclusion (LI) in the neuronal soma and swollen cord-like processes is a characteristic feature in the anterior horn cells and neurons in thoracic nucleus (Clarke) of familial amyotrophic lateral sclerosis (ALS) with posterior column involvement. We have studied the LI in the case of two sisters with this disorders. Microscopically the LI consists of an eosinophilic "core" surrounded by a basophilic "halo". Ultrastructurally the core consists of granule-associated filaments, while the halo consists of normal-looking neurofilament. Immunocytochemistry with anti-ubiquitin antibody shows that these granule-associated filaments in the core are highly ubiquitinated, while the normal-looking neurofilaments in the halo are not recognized by anti-ubiquitin antibody. Our study proves that LI consists of an aggregation of ubiquitinated filaments among a neurofilamentous accumulation, possibly representing a form of neuronal cytoskeletal disorganization in familial ALS.