Use of IMP3 in Identification of Carcinoma in Fine Needle Aspiration Biopsies of Pancreas

OBJECTIVE: To evaluate insulin-like growth factor-II mRNA binding protein 3 (IMP3), which is an oncofetal RNA-binding protein expressed in pancreatic carcinomas and detectable by immunohistochemistry, in diagnosis of pancreatic cancer. STUDY DESIGN: We retrospectively identified 25 consecutive pancreatic endoscopic ultrasound-guided fine needle aspiration biopsies with available cell blocks, including 12 invasive pancreatic ductal carcinomas and 13 cases of chronic pancreatitis. Immunostains were performed on 4-microm tissue sections using standard techniques. Cytoplasmic staining of the lesional cells and nonneoplastic pancreatic tissue was evaluated, and the intensity of staining was recorded as absent, weak, moderate or strong. RESULTS: Eleven (92%) adenocarcinomas demonstrated staining of tumor cells with IMP3. The staining reaction was weak in 2 of 11 (18%), moderate in 5 of 11 (45%) and strong in 4 of 11 (36%) of the cases. Nonneoplastic pancreatic tissues, present in 8 of 12 carcinomas and 13 cases of chronic pancreatitis, were negative for IMP3. CONCLUSION: IMP3 is a promising new marker with high specificity and sensitivity for pancreatic adenocarcinoma.