Pancreatic neuroendocrine tumors (PanNETs) are typically solid neoplasms but in rare instances may present as cystic lesions. This unusual presentation can make clinical diagnosis challenging. In addition, the clinical and histopathologic characteristics of cystic PanNETs are poorly defined. We identified 53 cystic PanNETs in our single-institution experience of 491 surgically resected PanNETs. Similar to solid PanNETs, cystic PanNETs developed with an equal sex distribution and over a wide age range (23 to 91 y; mean, 52 y). The unusual cystic appearance made radiologic differentiation from other cystic pancreatic neoplasms difficult with a misdiagnosis in 23 of 53 (43%) cases. An association between cystic PanNETs and multiple endocrine neoplasia type 1 or multifocal disease [5 of 53 (9%) and 7 of 53 (13%), respectively] was not observed as compared with solid PanNETs (P=0.34 and P=0.31, respectively). Grossly, cystic PanNETs were predominantly located in the tail of the pancreas (n=28, 53%) and were similar in size (mean, 3.3 cm) to solid PanNETs (mean, 4.1 cm; P=0.12). All cysts were unilocular (n=53, 100%) and filled with clear to straw-colored fluid. Larger cysts were sometimes noted to be hemorrhagic. Histologically, the cysts were lined by a thin fibrous band that separated the cyst from the neoplastic cells. In comparison with their solid counterparts, cystic PanNETs were less likely to demonstrate tumor necrosis (6%; P=0.04), perineural invasion (8%; P<0.001), vascular invasion (4%; P<0.001), regional lymph node metastasis (13%; P<0.001), and synchronous distant metastasis (4%; P=0.015). The neoplastic cells of the cystic PanNETs were well differentiated (n=53, 100%) with a low mitotic rate and low Ki-67 proliferation index (range, 0.2% to 11%; mean, 1.8%). On the basis of both the American Joint Cancer Committee and European Neuroendocrine Tumor Society staging systems, the majority of cystic PanNETs presented at a lower pathologic stage as compared with solid PanNETs. In summary, cystic PanNETs are a distinctive subgroup of PanNETs with unique clinical, radiographic, and pathologic features.

Objectives: The tall cell variant of papillary thyroid carcinoma (TCV-PTC) is an aggressive variant of PTC requiring accurate cytopathologic diagnosis for early aggressive management. Study Design: Twenty-five cases of TCV-PTC in which the tall cells comprised at least 30% of surgically resected tumor were included in the study. The direct smears from a preoperative fine needle aspiration (FNA) and available hematoxylin and eosin cell block sections were reviewed. Ten cases of TCV-PTC were randomly selected and blinded with an equal number of conventional PTC cases. Representative slides were independently reviewed by 7 cytologists. Results: In a majority of the cases, the FNA direct smears were hypercellular and displayed flat monolayer sheets of cells. Tall columnar cells with cytoplasmic tails were seen in 56% of cases. The presence of large polygonal follicular cells with abundant granular oncocytic cytoplasm and distinct cell borders was the most common feature seen in all cases. Seventeen (68%) cases displayed intranuclear pseudoinclusions in cells with abundant granular cytoplasm. A correct diagnosis of TCV-PTC was made in 30-40% of cases by 7 study participants. Conclusions: The correct recognition of TCV-PTC features in preoperative FNA is important for clinical management, and reporting these features in a cytopathology report is suggested.

Objectives-Expression of transcription factors that mediate epithelial-mesenchymal transition (EMT), such as Twist and Slug, is correlated with poor prognosis in many tumor types. Selected EMT markers were studied in a series of pancreatic ductal adenocarcinomas (PDAs) and benign pancreatic tissues to determine whether expression levels correlated with diagnosis, histologic grade, or patient outcome.Methods-Immunohistochemical stains for Twist, Slug, and N-cadherin were performed using a tissue microarray containing 68 PDAs and 38 samples of normal pancreas or chronic pancreatitis tissues.Results-Twist and Slug were identified in both the nucleus and cytoplasm of benign pancreatic ductal epithelium, chronic pancreatitis, and PDA. Compared with normal ductal epithelium, nuclear levels of Twist are decreased in PDA. None of the other EMT markers showed significant differences in staining indices among the diagnostic groups. There were no correlations between EMT marker expression and histologic grade. Epithelial-mesenchymal transition marker expression was not associated with N-cadherin expression, patient outcome, or duration of survival.Conclusions-Decreased expression of nuclear Twist is observed in malignant pancreatic epithelium. However, use of Twist as a diagnostic marker is precluded because decreased expression is also seen in chronic pancreatitis. None of the markers studied were predictive of patient outcome. Keywords epithelial-mesenchymal transition; pancreatic ductal adenocarcinomaDespite advances in radiologic imaging procedures, the diagnosis of pancreatic ductal adenocarcinoma (PDA) remains difficult, particularly for tumors of low stage. Invasive diagnostic procedures such as endoscopic ultrasonography or computed tomography-guided fine-needle aspiration or core biopsy often yield ambiguous diagnoses such as "atypical" or "suspicious for malignancy" when the tumor is of low histologic grade (well-differentiated) or when the amount of diagnostic material is limited. Tumor markers that assist in the pathologic diagnosis of PDA would be clinically useful in this frequent and challenging clinical distinction. MATERIALS AND METHODS Case RetrievalThe surgical pathology files at the Vanderbilt University Medical Center were searched for pancreatic resection specimens performed for either PDA or nonneoplastic disease with existing tissue blocks suitable for construction of a tissue microarray (TMA). A total of 72 cases were identified, 4 of which were resected for benign disease (2 secondary to trauma, 1 for a benign pancreatic neoplasm, and 1 for a benign stricture of the common bile duct). Patient charts were reviewed to record pathologic data (histologic grade, tumor location, tumor size, and pTNM status), demographic data (patient age and sex), and follow-up information (outcome and interval from date of surgical resection to death). The study protocol was approved by the institutional review boards at both Vanderbilt University and Dartmouth College. TMA ConstructionAll tissue samples were ...

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is a clinically effective neurosurgical treatment for Parkinson disease. Tissue reaction to chronic DBS therapy and the definitive location of active stimulation contacts are best studied on a postmortem basis in patients who have undergone DBS. The authors report the postmortem analysis of STN DBS following 5 years and 11 months of effective chronic stimulation including the histologically verified location of the active contacts associated with bilateral implants. They also describe tissue response to intraoperative test passes with recording microelectrodes and stimulating semimacroelectrodes. The results indicated that 1) the neural tissue surrounding active and nonactive contacts responds similarly, with a thin glial capsule and foreign-body giant cell reaction surrounding the leads as well as piloid gliosis, hemosiderin-laden macrophages, scattered lymphocytes, and Rosenthal fibers; 2) there was evidence of separate tracts in the adjacent tissue for intraoperative microelectrode and semimacroelectrode passes together with reactive gliosis, microcystic degeneration, and scattered hemosiderin deposition; and 3) the active contacts used for approximately 6 years of effective bilateral DBS therapy lie in the zona incerta, just dorsal to the rostral STN. To the authors' knowledge, the period of STN DBS therapy herein described for Parkinson disease and subjected to postmortem analysis is the longest to date.

BACKGROUND: Intrapancreatic accessory spleen (IPAS) is a rare benign lesion of the pancreas that frequently clinically and radiographically mimics a solid neoplasm. Very rarely, epidermoid cysts may form in IPAS and be mistaken for a cystic neoplasm of the pancreas on radiographic imaging. IPAS and epidermoid cyst involving intrapancreatic cyst (ECIPAS) are benign, and, if recognized, do not require surgical intervention. There are few reports of the cytopathologic features of IPAS diagnosed by fine‐needle aspiration (FNA). METHODS: Here we report a series of 6 cases of endoscopic ultrasound (EUS)‐guided FNA of IPAS, 3 of which had histological confirmation, including 1 case of histologically confirmed ECIPAS. RESULTS: Cytomorphologic features of IPAS include a polymorphous population of hematopoietic cells, including lymphocytes, eosinophils, histiocytes, plasma cells, and red blood cells, admixed with numerous small blood vessels representing splenic sinusoids. CD8 immunostaining of cell block or core biopsy material highlights splenic endothelial cells and confirms the diagnosis. FNA of ECIPAS reveals predominantly macrophages and proteinaceous debris. CONCLUSIONS: Diagnostic pitfalls include pancreatic neuroendocrine tumor. If IPAS is recognized as a diagnostic consideration on EUS‐FNA, unnecessary surgical resection may be avoided. Cancer (Cancer Cytopathol) 2012. © 2012 American Cancer Society.