[419] Role of Molecular Analysis on Classification of Pancreatic Cystic Lesions (PCLs) without Definitive Cytological Diagnoses

Qiusheng Si, Paula Rodriguez-Urrego, Arnold H Szporn, Maoxin Wu. Mount Sinai School of Medicine, New York, NY

Background: The clinical management of patients with PCLs has relied on pathologic diagnoses. Non-mucinous PCLs are usually followed clinically, while some mucinous PCLs require surgical resection. Enodoscopic ultrasound-guided fine needle aspiration and cytological examination are the predominant methods used to evaluate the PCLs. However, a definitive cytological diagnosis(non-mucinous vs. mucinous) can not be rendered in some cases due to the lack of diagnostic cells in the specimen. Recently, molecular analysis of cyst fluid from PCLs has been available (PathFinderTG®, Pittsburgh, PA). The purpose of this study is to determine if molecular analysis would be useful to further classify PCLs which do not have a definitive cytological diagnosis.
Design: Between January 2006 and September 2012, we identified 87 PCLs which met the study criteria. Molecular analyses looking for quality and quantity of DNA, loss of chromosome homogeneity and K-ras mutations,were reviewed and the cases were further classified into non-mucinous, mucinous and malignant. Correlation with the clinical follow-up and surgical pathology of all cases was performed.
Results: Of 87 cases, 82 (94.3%) cases were able to be further classified into non-mucinous (50, 60.1%), mucinous (30, 36.5%) and malignant (2, 2.4%) by molecular analysis. In 50 non-mucinous cases, 9 cases had surgical resection and 20 cases had clinical follow-up. Of 9 resected cases, 4 were serous cystadenoma (SCA) and 5 were mucinous neoplasm (2 mucinous cystic neoplasm (MCN) and 3 IPMN). In 30 mucinous cases, 8 cases had surgical resection and 15 cases had clinical follow-up. Of 8 resected cases, 7 were mucinous neoplasm (4 MCN and 3 IPMN) and 1 was SCA. Of 2 malignant cases, one was diagnosed as mucinous adenocarcinoma on a repeat FNA and the other one was suspicious for malignancy on follow-up image study. Using the diagnoses of the 17 surgical resection specimens as gold standards, the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of molecular analysis were 66.7%, 58.3%, 44.4%, 87.5% for non-mucinous PCLs and 58.3%, 80%, 87.5%, 44.4% for mucinous PCLs, respectively. The overall diagnostic accuracy of molecular testing was 64.7%.
Conclusions: Molecular analysis of PCLs cyst fluid has some diagnostic value for cases without definitive cytological diagnosis. Molecular analysis has better sensitivity and NPV for non-mucinous PCLs and better specificity and PPV for mucinous PCLs. However, a multidisciplinary approach is needed in the management of these patients.
Category: Cytopathology

Tuesday, March 5, 2013 1:00 PM

Poster Session IV # 73, Tuesday Afternoon


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