Numerous, Fine, Clear, Cytoplasmic Vacuoles May Be a Helpful Cytologic Feature in the Diagnosis of Pancreatic Endocrine Neoplasm on Pancreatic Endoscopic Ultrasound-Guided Fine Needle Aspiration
MR Steciuk, N Jhala, D Jhala. University of Alabama at Birgmingham, Birmingham, AL
Background: Pancreatic Endocrine Neoplasm (PEN) and Solid Pseudopapillary Neoplasm (SPN) are difficult to differentiate on fine needle aspirates of the pancreas and therefore comprise a common differential diagnosis in fine needle aspiration (FNA) or endoscopic ultrasound guided fine needle aspiration (EUS-FNA). Both entities produce numerous single plasmacytoid cells on cytologic smears. We have previously reported that large clear cytoplasmic vacuoles (LCCVs) can serve as a clue to favor the diagnosis of SPN and also noted that fine, clear, cytoplasmic vacuoles (FCCVs) could be seen in PEN and SPN, but that these tended to be more numerous in PEN. The current study attempts to determine whether the presence of numerous FCCVs can discriminate between PEN and SPN.
Design: We retrieved all the cases for PEN (n=17), SPN (n=7), and metastatic renal cell carcinoma (n=2) from the teaching files of our institution (performed in the context of pancreatic EUS-FNA) and reviewed Wright-stained smears for the presence or absence of numerous FCCVs, defined as vacuoles that were 1) round cytoplasmic inclusions, 2) optically clear, 3) smaller in size than the nucleus of a red cell, 4) present in sufficient number such as to partially obscure the nucleus (usually greater than 10), and 5) present in a majority of cells in at least one high power field. FNA diagnosis was based on published cytologic criteria with immunohistochemical confirmation in all cases. Some, but not all, cases were confirmed on subsequent surgical excision.
Results: We found that numerous FCCVs, as defined above, were present in approximately half (8/17) of the PEN and none of the SPN (0/7), (X2 = 4.941; p = 0.0262). One caveat, besides the small number of SPN in this study is the possibility of metastatic renal cell carcinoma to the pancreas, which we found will also produce numerous FCCVs. Careful attention to other cytologic characteristics, particularly the lack of numerous single plasmacytoid cells, can help the cytologist avoid this pitfall. The possibility that the clear-cell variant of PEN, associated with Von Hippel-Lindau syndrome, may be overrepresented should also be considered.
Conclusions: These results are encouraging that the presence of strictly defined numerous FCCVs may be useful in discriminating PEN from SPN on Wright-stained smears on FNA and EUS-FNA.
Monday, March 22, 2010 9:30 AM
Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 55, Monday Morning