Faculty Bibliography

BACKGROUND: Noninvasive encapsulated follicular variant of papillary thyroid carcinoma, a diagnosis implying malignancy as a variant of papillary thyroid carcinoma (PTC), has recently been reclassified to noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) on surgical pathology. Due to the effects of such a recategorization on rate of malignancy and clinical management algorithms, it is imperative that we explore whether presurgical fine-needle aspiration can differentiate NIFTP from PTC and follicular adenoma (FA). METHODS: Cytology slides from subjects with final surgical pathology resection diagnoses of NIFTP/encapsulated follicular variant of papillary thyroid carcinoma, classic PTC, and FA made between January 2013 and August 2016 were assessed. The Bethesda System diagnoses were tabulated and cytomorphologic features were analyzed for an association with surgical pathology diagnoses. RESULTS: A total of 56 NIFTP, 67 classic PTC, and 30 FA cases were included. The presurgical NIFTP diagnosis according to The Bethesda System was most often atypia of undetermined significance (37.5%) followed by suspicious for follicular neoplasm/follicular neoplasm (26.8%), suspicious for malignancy (17.9%), benign (10.7%), and positive for malignancy (7.1%). The most common NIFTP cytomorphologic features were nuclear enlargement (83.9%), nuclear crowding (82.1%), nuclear clearing (69.6%), and microfollicles (73.2%). All cytomorphologic features demonstrated statistically significant associations (P value range, <.001-.002) between NIFTP and PTC, whereas select cytomorphologic features demonstrated significant associations between NIFTP and FA. CONCLUSIONS: Several statistically significant associations appear to be present between cytomorphologic features and surgical diagnosis that may be used as clues to distinguish NIFTP, PTC, and FA on fine-needle aspiration. Although diagnostic confirmation of NIFTP must occur at the time of excision, similar to follicular neoplasms, the possibility of NIFTP may be raised preoperatively on cytology. Cancer Cytopathol 2017;125:378-88. (c) 2017 American Cancer Society.

Cytologic diagnosis of extra-adrenal paraganglioma presenting as a peripancreatic mass is challenging with a high error rate due to its rarity. We report two cases of peripancreatic masses identified by radiology. Endoscopic ultrasound-guided fine needle aspiration (FNA) of the masses showed a moderately cellular tumor composed of small to medium sized neoplastic cells with round to oval nuclei, arranged singly and in loose clusters. Focal rosette-like structures were present. The cells were positive for neuroendocrine markers (synaptophysin and chromogranin). A diagnosis of a neoplasm with neuroendocrine differentiation and neuroendocrine tumor was made respectively on FNA for each case. The subsequent surgical resection of the tumors revealed peripancreatic paraganglioma. Although paraganglioma has been reported in the literature, the detailed comparison of perpancreatic paraganglioma versus pancreatic/gastrointestinal neuroendocrine tumor is still lacking. Therefore using these two cases with literature review, we wish to illustrate the differential diagnosis between these two entities based on cytomorphology and immunohistochemical study.

Objectives: Differentiating squamous cell carcinoma from adenocarcinoma (ACA) in cytology specimens can be challenging. Recent literature showed p40 had higher specificity than p63 for this purpose. Methods: We identified 190 cytology cases with p40 (polyclonal) and p63 (monoclonal clone 4A4) immunohistochemistry, including specimens from fine-needle aspirations (FNAs) and effusions. Results: ACAs of lung origin stained for p40 and p63 in 21% and 20% of cases, respectively, regardless of specimen site. Among lung FNAs of primary pulmonary ACAs (n = 42), 14% were positive for p40 and 24% were positive for p63. Of the 20 pulmonary ACAs in effusions, more cases showed p40 positivity (40%) compared with FNAs, whereas p63 were positive in 15%. Among metastatic ACAs from other sites (n = 14), more cases were positive for p40 than p63. Conclusions: Polyclonal p40 yields a level of false positivity in ACAs similar to p63, which is highest in effusions and is not limited to lung origin.