[373] Intraductal Tubulopapillary Neoplasm (ITPN) of Pancreas: Is Molecular Analysis of Cyst Fluid a Useful Adjunct in Distinguishing This Newly Recognized Tumor from Intraductal Papillary Mucinous Neoplasm (IPMN)?

Huimin Guo, Susie Nguyen, Pedro deBrito, Nadim Haddad, Mary Sidawy. Georgetown University Hospital, Washington, DC

Background: ITPN was recently recognized as a distinct pancreatic tumor (WHO 2010). It is a rare indolent neoplasm that may be associated with dysplasia or invasive carcinoma. The main differential diagnosis of ITPN is IPMN as both tumors are intraductal and present with solid and cystic components. Histologically, ITPN is characterized by tubulopapillary and cribriform architecture and absent mucin. However, its cytomorphology and molecular aberrations have not yet been well described. This study presents the cytologic features of 2 cases of ITPN and compares the results of their molecular analysis with other pancreatic cystic lesions.
Design: Our database was searched from August 2010-April 2012 for endoscopic ultrasound-guided fine-needle aspirations (FNA) of pancreatic cystic lesions with available histologic follow-up and molecular analysis of the fluid [KRAS point mutations & tumor suppressor genes (LOH)]. Eight cases were identified, 2 of which histologically confirmed ITPN. The cytologic features of ITPN were evaluated and the molecular analyses, cytologic and histologic results were reviewed.
Results: Histologic diagnoses included 2 ITPN, 1 pseudocyst & 5 IPMN. Table 1 summarizes the cytohistologic correlation and results of fluid analysis. FNA of ITPN were cellular with a prominent tubular and cribriform architecture and absent mucin (Fig. 1). KRAS mutations were not detected in ITPN or pseudocyst, but were detected in all 5 IPMN, 4 of which had nondiagnostic FNA.

Surgical DxFNA DxDNA QuantityKRASLOH
ITPN+insitu ACFavor ITPN+++(-)(-)
PseudocystCyst contents++(-)(-)
IPMN-LGMucinous lesion++(+)(-)
ND=Nondiagnostic; AC= Invasive adenoca; LG=low grade dysplasia; ++= Moderate; +++= Highest;

Conclusions: The cytologic features of ITPN, namely lack of mucin coupled with tubulopapillary and cribriform architecture, are distinctive. In contrast to IPMN, KRAS mutations were not detected in ITPN. Our results suggest that cytomorphology along with molecular analysis can distinguish ITPN from IPMN.
Category: Cytopathology

Tuesday, March 5, 2013 1:00 PM

Poster Session IV # 80, Tuesday Afternoon


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