IMP3/L523S

Pathology

 IMP3 antibody is a highly specific marker for malignant lesions.

Differentiating reactive mesothelial cells from metastatic carcinoma and malignant mesothelioma is critical in effusion cytology.

Numerous immunohistochemical/cytochemical reports use various antibodies in effusion samples, and most antibodies differentiate metastatic adenocarcinoma from malignant mesothelioma, but no antibodies help distinguish malignant mesothelioma from reactive mesothelial cells.

A mouse monoclonal antibody (IMP3/L523S) against KOC is a 580-amino acid oncofetal RNA-binding protein containing 4 K homology domains.

IMP3/L523S has been identified in several human malignant tumors.

IMP3 immunoreactivity is observed in 5.1% of reactive mesothelial cells, 72.6% of malignant effusion, 36.4% of malignant mesothelioma, 75.7% of metastatic adenocarcinoma, and 100% of squamous cell carcinoma.

The overall specificity for the diagnosis of malignancy was 94.9%, whereas the sensitivity was 72.6%.

In the peritoneal effusions, the sensitivity for the diagnosis of metastatic adenocarcinoma to distinguish reactive mesothelial cells was 92.3%.

IMP3 staining is present in many carcinomas and is not a useful marker for distinguishing between carcinomas arising in different organs.

However, the IMP3 antibody is a highly specific marker for malignant lesions, and thus, IMP3 staining is useful for distinguishing neoplastic cells from reactive mesothelial cells in effusion samples.

References

 IMP3/L523S, a novel immunocytochemical marker that distinguishes benign and malignant cells: the expression profiles of IMP3/L523S in effusion cytology. Ikeda K, Tate G, Suzuki T, Kitamura T, Mitsuya T. Hum Pathol. 2010 Jan 6. PMID: 20060157