Analyses of proliferative potential in schwannomas.
We report studies of schwannomas with a high percentage of MIB-1 positive cells. Thirty-eight specimens from 36 cases of schwannoma in the intracranial and spinal regions comprise the substance of this study. The MIB-1 positive cells were measured using immunohistochemical staining. In nine cases with a positivity index (PI) of 5% or more, immunohistochemical staining using DNA topoisomerase IIalpha (topo-II) and CD68 was performed. In some cases, we also searched for apoptosis with the TdT-mediated dUTP-biotin nick-end labeling (TUNEL) method. Three of nine cases with 5% or more positive MIB-1 cells had a very high cellularity with mitotic figures and were considered cellular Schwannomas. Their MIB-1 PI values were 8.21%, 10.00%, and 21.37%. However, the remaining six cases showed little evidence of malignancy. Their PIs were comparatively low, ranging from 5.19% to 8.41%, and the positive findings were localized in many cases. In these cases, we examined the sites where MIB-1 was measured and found that they corresponded to the borderline site between Antoni type A and B patterns and tended to be associated with an infiltration of CD68-positive macrophage. Furthermore, apoptotic cells appeared in the sites. With topo-II staining, the PIs in the same sites of these six cases were low, ranging from 0.78% to 1.93%. This implies that the high MIB-1 PI that was seen in these six cases was caused by reaction of MIB-1 to tumor cells that brought about an abnormality in the cell cycle by degeneration, such as apoptosis. In the site of formation of Antoni type B, MIB-1 may be a false positive in tumors with degenerative findings such as schwannomas. Topo-II was useful in these cases.
Abe
M
M
Department of Pathology, Fujita Health University, School of Medicine, Toyoake, Aichi, Japan. masabe@fujita-hu.ac.jp
Kawase
T
T
Urano
M
M
Mizoguchi
Y
Y
Kuroda
M
M
Kasahara
M
M
Suzuki
H
H
Kanno
T
T
D000328:Adult; D000368:Aged; D034961:Antigens, Nuclear; D001932:Brain Neoplasms / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology*; D002455:Cell Division; D003056:Cochlear Nerve; D003390:Cranial Nerve Neoplasms / Q000378:metabolism / Q000473:pathology*; D004250:DNA Topoisomerases, Type II / Q000378:metabolism; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D019394:Ki-67 Antigen; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009442:Neurilemmoma / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology*; D009687:Nuclear Proteins / Q000378:metabolism; D013125:Spinal Neoplasms / Q000378:metabolism / Q000473:pathology*; D013194:Staining and Labeling
D034961:Antigens, Nuclear; D019394:Ki-67 Antigen; D009687:Nuclear Proteins; D004250:DNA Topoisomerases, Type II