title: Cotton wool plaques in non-familial late-onset Alzheimer disease.
abstract: Cotton wool plaques (CWP) are large, ball-like plaques lacking dense amyloid cores that displace adjacent structures. They were first described in a Finnish kindred with early-onset Alzheimer disease (AD) with spastic paraparesis due to a presenilin-1 delta9 mutation. We describe a case of sporadic late-onset AD with numerous neocortical CWP as well as severe amyloid angiopathy and marked leukoencephalopathy, compared with 16 cases of late-onset AD with similar degrees of amyloid angiopathy and leukoencephalopathy. The cases were studied with histologic methods and with single and double immunostaining for beta-amyloid (Abeta), paired helical filaments-tau (PHF-tau), neurofilament (NF), glial fibrillary acidic protein (GFAP), HLA-DR, and amyloid precursor protein (APP). We found that CWP were well-circumscribed amyloid deposits infiltrated by ramified microglia and surrounded by dystrophic neurites that were immunopositive for APP, but only weakly for NF and PHF-tau. Abeta1-12 was diffuse throughout the CWP, while Abeta37-42 was peripherally located and Abeta20-40 more centrally located. Two of the 16 late-onset AD cases also had CWP, but they were also admixed with diffuse plaques and plaques with dense amyloid cores. Pyramidal tract degeneration was not a consistent finding or a prominent feature in any case. The results suggest that CWP are not specific for early-onset familial AD with spastic paraparesis.
authors.affiliation: Department of Pathology, Mayo Clinic, Jacksonville, Florida 32224, USA.
authors.forename: T V
authors.initials: TV
authors.lastname: Le
authors.forename: R
authors.initials: R
authors.lastname: Crook
authors.forename: J
authors.initials: J
authors.lastname: Hardy
authors.forename: D W
authors.initials: DW
authors.lastname: Dickson
mesh_terms: D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000235:genetics / Q000473:pathology*; D016229:Amyloid beta-Peptides / Q000032:analysis; D016564:Amyloid beta-Protein Precursor / Q000032:analysis; D001921:Brain / Q000473:pathology*; D005260:Female; D005838:Genotype; D005904:Glial Fibrillary Acidic Protein / Q000032:analysis; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000032:analysis / Q000235:genetics; D017628:Microglia / Q000737:chemistry / Q000473:pathology; D008875:Middle Aged; D016501:Neurites / Q000737:chemistry / Q000473:pathology; D016900:Neurofilament Proteins / Q000032:analysis; D020336:Paraparesis, Spastic / Q000473:pathology; D053764:Presenilin-1; D011712:Pyramidal Tracts / Q000473:pathology
chemical_list: D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D005904:Glial Fibrillary Acidic Protein; D008565:Membrane Proteins; D016900:Neurofilament Proteins; C508853:PSEN1 protein, human; D053764:Presenilin-1