IMP3 as a supplemental diagnostic marker for Hodgkin lymphoma

Insulin-like growth factor II mRNA-binding protein 3 (IMP3) is ubiquitously expressed in embryos, mediating organogenesis, RNA trafficking, and cell growth, and is generally down-regulated in adult tissue. However, IMP3 has recently been shown to be overexpressed in some malignant epithelial neoplasms and to be a useful diagnostic and/or prognostic biomarker for several carcinomas. To determine whether IMP3 might also be an accurate biomarker of Hodgkin lymphoma, we examined 81 Hodgkin lymphomas for immunoreactivity to IMP3 as compared to commonly used markers such as CD30, CD15, PAX5, and MUM1. Consequently, in 98.8% (80/81) of Hodgkin lymphomas, the malignant Hodgkin and Reed-Sternberg cells were selectively reactive for IMP3, with 72.8% (59/81) of the tumors showing strong, diffuse cytoplasmic staining. Positive staining of the Hodgkin lymphomas was also seen for CD30 (82.7%, 67/81), CD15 (65.4%, 53/81), PAX5 (84.0%, 68/81), and MUM1 85.2% (69/81), but significantly fewer cells showed strong staining intensity for CD30 (32.1%, 26/81), CD15 (17.3%, 14/81), PAX5 (12.3%, 10/81), and MUM1 (29.6%, 24/81). Furthermore, the IMP3 staining was selectively restricted to Hodgkin and Reed-Sternberg cells, with a clearly negative background, and complementary to CD30 staining. Our findings show that IMP3 may be a useful diagnostic marker of Hodgkin lymphoma, helping to improve diagnostic accuracy for this malignancy.