title: Diversity of glial cell components in pilocytic astrocytoma.
abstract: To characterize the cellular density and proliferative activity of GFAP-negative cells in pilocytic astrocytoma (PA), surgically excised tissues of PAs (n=37) and diffuse astrocytomas (DAs) (n=11) were examined morphologically and immunohistochemically using antibodies against GFAP, Olig2, Iba1 and Ki-67 (MIB-1). In PA, Olig2 immunoreactivity was significantly expressed in protoplasmic astrocytes in microcystic, loose areas and cells in oligodendroglioma-like areas. Iba1-positive, activated microglia/macrophages were also commonly observed in microcystic areas. In compact areas, a prominent reaction for GFAP was observed, but for Olig2 and Iba1 to a lesser degree. On semiquantitative analysis, the number of Olig2-positive cells was significantly higher in PAs (mean labeling index (LI) +/- standard deviation (SD): 46.8+/-15.4%) than in DAs (13.3+/-7.8%) (P<0.001). Many Iba1-positive, microglia/macrophages were observed in PAs (19.9+/-6.5%), similarly to DAs (20.9+/-9.9%). Re-immunostaining of PA demonstrated that most Ki-67-positive, proliferating cells expressed Olig2, whereas GFAP or Iba1 expression in Ki-67-positive cells was less frequent (14.7+/-13.7%, and 8.8+/-13.6%) in a double immunostaining study. Conversely, the percentage of Olig2-positive, proliferating cells in total Olig2-positive cells (7.2+/-3.9%) was higher than that of Iba1-positive, proliferating cells in total Iba1-positive cells (0.9+/-0.6%). In conclusion, the present study found that PA consisted of numerous GFAP-negative cells, including Olig2-positive cells with high proliferation. Semiquantitative analysis of Olig2 immunohistochemistry in microcystic areas might therefore be useful for the differential diagnosis of PA and DA.
authors.affiliation: Department of Human Pathology, Gumma University Graduate School of Medicine, Maebashi, Gumma, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Atsushi
authors.initials: A
authors.lastname: Sasaki
authors.forename: Shogo
authors.initials: S
authors.lastname: Ishiuchi
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Nakazato
mesh_terms: D000328:Adult; D000368:Aged; D001254:Astrocytoma / Q000378:metabolism* / Q000473:pathology; D051792:Basic Helix-Loop-Helix Proteins / Q000096:biosynthesis*; D014408:Biomarkers, Tumor / Q000032:analysis*; D001932:Brain Neoplasms / Q000378:metabolism* / Q000473:pathology; D002135:Calcium-Binding Proteins; D002648:Child; D002675:Child, Preschool; D004268:DNA-Binding Proteins / Q000096:biosynthesis; D003937:Diagnosis, Differential; D005260:Female; D005904:Glial Fibrillary Acidic Protein / Q000096:biosynthesis; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D007223:Infant; D007231:Infant, Newborn; D019394:Ki-67 Antigen / Q000096:biosynthesis; D008297:Male; D008840:Microfilament Proteins; D008875:Middle Aged; D009419:Nerve Tissue Proteins / Q000096:biosynthesis*; D009457:Neuroglia / Q000378:metabolism* / Q000473:pathology; D000076104:Oligodendrocyte Transcription Factor 2
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D014408:Biomarkers, Tumor; D002135:Calcium-Binding Proteins; D004268:DNA-Binding Proteins; D005904:Glial Fibrillary Acidic Protein; D019394:Ki-67 Antigen; D008840:Microfilament Proteins; D009419:Nerve Tissue Proteins; D000076104:Oligodendrocyte Transcription Factor 2; C112986:AIF1 protein, human; C405708:OLIG2 protein, human