[410] Fine Needle Aspiration Biopsy Cytology of 42 Cases of Intraductal Papillary Mucinous Neoplasm.

James C Mathews, Hannah R Krigman. Washington University School of Medicine, St. Louis, MO

Background: Intraductal papillary mucinous neoplasm (IPMN) is often first sampled by endoscopic ultrasound guided fine needle aspiration biopsy (FNA). Early diagnosis of IPMN is advantageous because up to 35% of IPMN are associated with foci of adenocarcinoma. Previous studies offer conflicting results on the clinical utility of FNA in the evaluation of IPMN. Most series study fewer than 30 cases. We undertook a retrospective analysis of resection proven IPMN to determine which FNA findings are diagnostic of IPMN and whether the grade of dysplasia and presence of invasive carcinoma can be predicted.
Design: Resections of IPMN previously sampled by FNA within two years were retrieved from our database. Parameters assessed in FNA specimens included: quality of mucin, nuclear, cytologic, and overall atypia, group architecture, necrosis and inflammation. The resection specimens were separately reviewed and graded by currently accepted criteria. The FNA and histologic diagnoses were correlated to determine the features important in the cytologic evaluation of IPMN.
Results: 42 FNA specimens corresponded to 41 cases of IPMN. FNA diagnoses were adenocarcinoma (29%), mucinous cystic lesion (39%), acellular (19%), benign epithelium (21%), and low grade ductal lesion (2%). 26 IPMN (63%) and 15 IPMN associated with invasive adenocarcinoma (37%) were resected. Enteric type epithelium (50%) was most common with gastric (34%) and pancreatobilliary (11 %) types seen in the remainder. IPMNs classified as mild, moderate and severe dysplasia accounted for 28%, 36% and 26% respectively. FNA characteristics suggesting the diagnosis of IPMN included presence of mucin (86%), thick "colloid-like" mucin (55%), papillary groups (36%), and finger-like projections (31%). Nuclear enlargement, pleomorphism, cytoplasmic vacuolation, and nucleoli were included as atypia. Atypia was absent in 38%, mild in 10%, moderate in 7% and severe (adenocarcinoma) in 31% of FNA.
Conclusions: While the diagnosis of IPMN is suggested by FNA, definitive diagnosis of the neoplasm remains problematic, in part due to sampling issues. The presence of thick "colloid-like" mucin and delicate papillae are suggestive of the diagnosis on IPMN, but do not correlate with the grade of dysplasia or presence of malignancy. At the same time, FNA can be extremely specific in identifying severe atypia which is highly predictive of invasive carcinoma and may guide the surgical and medical management of the patient.
Category: Cytopathology

Tuesday, March 1, 2011 9:30 AM

Poster Session III # 63, Tuesday Morning


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