The diagnostic value of Ki-67 and repp86 in distinguishing between benign and malignant mesothelial proliferations.
BACKGROUND
The differentiation of benign mesothelial proliferations from malignant mesotheliomas may be difficult, especially when evaluating small specimens from pleural biopsies.


OBJECTIVE
To explore the potential value of 2 proliferative cell markers, Ki-67 and restrictedly expressed proliferation-associated protein 86 kDa (repp86), in distinguishing between malignant mesothelioma (MM) and benign reactive mesothelial hyperplasia (MH).


METHODS
Thirty-six cases of MM from 26 men and 10 women with a mean age of 62.9 years (range, 36-80 years) and 22 cases of benign reactive MH from 14 male and 8 female patients with a mean age of 51.5 years (range, 15- 88 years) were included in this study. The proliferative status of the lesions was assessed by immunohistochemistry using monoclonal antibodies to Ki-S2 (repp86) and Ki-S5 (Ki-67). The labeling indices were quantified.


RESULTS
The mean labeling indexes for Ki-67 in MM and benign reactive MH were 24.6% (range, 1%-66%) and 6.23% (range, 0%-25%), respectively. The mean labeling indexes for repp86 in MM and benign reactive MH were 26.3% (range, 0%-50%) and 3.26% (range, 0%- 21%), respectively. The average proliferative cell count was significantly higher in MM compared with benign reactive MH (P < .001). Furthermore, both markers showed a significant correlation in their expression in MM and benign reactive MH (r = 77.5, P < .001). Sensitivities of 88% and 92% and specificities of 92% and 94% were obtained at a cutoff point of 9% for Ki-67 and repp86, respectively.


CONCLUSIONS
Used in combination, Ki-67 and repp86 appear to be useful markers in differentiating MM from benign reactive MH.
Taheri
Zohreh Mohammad
ZM
National Research Institute of Tuberculosis and Lung Disease, Department of Pathology, Shahid Beheshti University of Medical Sciences, Tehran, Iran. mtaheri@nritld.ac.ir
Mehrafza
Mehdi
M
Mohammadi
Forozan
F
Khoddami
Maliheh
M
Bahadori
Moslem
M
Masjedi
Mohammad Reza
MR
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000911:Antibodies, Monoclonal / Q000276:immunology; D015415:Biomarkers / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000378:metabolism; D049109:Cell Proliferation; D003937:Diagnosis, Differential; D004720:Endonucleases; D004848:Epithelium / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006801:Humans; D006965:Hyperplasia / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology; D019394:Ki-67 Antigen / Q000276:immunology / Q000378:metabolism*; D008297:Male; D008654:Mesothelioma / Q000175:diagnosis* / Q000378:metabolism* / Q000473:pathology; D008875:Middle Aged; D018301:Neoplasms, Mesothelial / Q000175:diagnosis* / Q000378:metabolism* / Q000473:pathology; D009687:Nuclear Proteins / Q000276:immunology / Q000378:metabolism*; D012680:Sensitivity and Specificity
D000911:Antibodies, Monoclonal; D015415:Biomarkers; D014408:Biomarkers, Tumor; D019394:Ki-67 Antigen; D009687:Nuclear Proteins; D004720:Endonucleases; C095221:SND1 protein, human