Article

Oncofetal protein IMP3, a new diagnostic biomarker to distinguish malignant mesothelioma from reactive mesothelial proliferation.

Department of Pathology, University of Massachusetts Medical Center, One Innovation Drive, Worcester, MA 01605, USA.
The American journal of surgical pathology (Impact Factor: 4.06). 06/2011; 35(6):878-82. DOI: 10.1097/PAS.0b013e318218985b
Source: PubMed

ABSTRACT The distinction of malignant mesothelioma from reactive mesothelial proliferation remains to be a major challenge for surgical pathologists. In this study, we investigated whether insulin-like growth factor II messenger ribonucleic acid-binding protein 3 (IMP3), an oncofetal protein, can be used as a biomarker to distinguish between malignant and reactive mesothelial cells. A total of 109 cases (mesothelioma, n=45; reactive mesothelial proliferation, n=64) were examined by immunohistochemistry for IMP3 expression. IMP3 showed strong cytoplasmic staining in 33 of 45 (73%) mesothelioma cases. In contrast, the expression of IMP3 was undetectable in all (64 cases) benign reactive mesothelial proliferations. Among the IMP3-positive mesotheliomas, 27 (82%) exhibited diffuse IMP3 expression. The vast majority of IMP3-positive subtypes of mesotheliomas showed IMP3 expression in >50% of malignant cells, as this diffuse staining pattern occurred in 17 (81%) cases of epithelial, 4 (100%) cases of sarcomatoid, and 6 (75%) cases of mixed types of mesothelioma. In addition, 2 cases, which were initially diagnosed as atypical mesothelial proliferations and later confirmed to be mesotheliomas, showed diffuse IMP3 expression. Our findings suggest that IMP3 is a new positive biomarker for malignant mesothelioma. IMP3 immunohistochemical staining can be used as an adjunct tool in the distinction of malignant mesothelioma from reactive mesothelial proliferations.

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