Endoscopic ultrasound-guided fine needle aspiration of solid masses: histologic and immunohistochemical evaluation

Background:

Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) has been widely demonstrated to be a useful to diagnose lesions adjacent to the gastrointestinal tract, especially around peripancreatic area. Immunohistochemical analysis of EUS-FNA specimens gives valuable information if combined with a cytopathologic analysis. Without on-site pathologist, histologic specimen not cytologic smear can be used for immunohistochemical analysis.

Objective:

The aim of this study is to evaluate the clinical utility of histologic specimen obtained by EUS-FNA, especially in the aspect of immunohistochemical analysis of tissue samples.

Design: A retrospective single center study

Methods:

From January 1, 2009 to July 14, 2010, tissue samples were harvested for both cytologic smear and histologic analysis in 115 patients undergoing EUS-FNA of solid masses. Immunohistochemical stains were performed if a pathologist thought it would be a help for a diagnosis. The final diagnosis was based on histologic examination of biopsies/resected pathology materials (n=109) and clinical follow up (n=7) at least six months apart.

Results:

Of 116 EUS-FNAs (115 patients, male 56%, female 44%), 93 FNAs were from the pancreas, 10 from the gastrointestinal tract, and 13 from adjacent structure (Lymph node, Biliary tract and Retroperitoneum). Final diagnoses were: malignancy (n=90), benign (n=9) and borderline such as neuroendocrine tumor, GIST etc (n=17). Overall sensitivity of cytologic smear, histologic analysis and combined analysis were 70.4%, 67.8% and 82.6%. Sensitivity between cytological smear and combined analysis were statistically different (p<0.001). Immunohistochemistry was performed in 26 patients with histological specimen. 13 patients with inconclusive cytologic smear were diagnosed through histological and immunohistochemical analysis. In 7 of them, the diagnoses could be made after immunohistochemical analysis

Conclusion:

At EUS-FNA in solid masses, combined cytologic-histologic analysis showed significant higher sensitivity than cytology alone without on-site pathologist. Immunohistochemistry for tissues obtained by EUS-FNA could be done in histological analysis if it was needed after examination of specimen.