Cytologic criteria to reduce error in EUS-FNA of solid pseudopapillary neoplasms of the pancreas.

INTRODUCTION: Standardization of error classification in pathology remains an important issue. This study assesses the extent of error in cytopathologic diagnosis of solid pseudopapillary neoplasms (SPN) of the pancreas. Because of morphologic overlap of SPN and pancreatic neuroendocrine neoplasms (NET), we compared cytologic characteristics to determine which best distinguishes these entities. MATERIALS AND METHODS: We collected cases diagnosed as SPN either by endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) by cytology or surgical pathology from January 2000 to March 2013. An equal number of NET cases were randomly selected. Cytology and surgical pathology cases were evaluated for diagnostic errors and patient impact. Cytologic features in SPN and NET were scored based on presence of previously described characteristics. RESULTS: A total of 17 patients with EUS-FNA were diagnosed with SPN by cytology or surgical pathology. Of those, 14 had surgical follow-up and 13 had adequate cell blocks and immunohistochemistry. There were 5 discrepancies between cytology and surgical pathology (5 of 14, 36%). There were no false positives or false negatives, but 5 misclassifications: 4 diagnosed as NET on cytology, and 1 as NET versus SPN. All misclassification errors were associated with no harm. When compared with NET, fine chromatin, nuclear grooves, pseud papillae, pink stroma, and hyaline globules are statistically significantly associated with SPN. CONCLUSIONS: EUS-FNA of pancreatic SPN has excellent positive and negative predictive value, with no false positives or false negatives in this 12-year study. Only misclassification errors as pancreatic NET were made with minimal impact. We suggest that the presence of 3 of 5 major cytologic criteria offer accuracy in diagnosing SPN to prevent misclassification.

Idiopathic follicular mucinosis or mycosis fungoides? classification and diagnostic challenges.

In recent years, the distinction between idiopathic follicular mucinosis (FM) and lymphoma-associated follicular mucinosis (LAFM) has been made through assessment of T-cell receptor gene rearrangement, flow cytometry, and immunohistochemistry. These methods, among others, have mostly identified monoclonality as a defining characteristic of LAFM; however, this finding cannot be considered conclusive, as monoclonality also has been described in benign inflammatory dermatoses such as lichen planus and idiopathic FM. Pure histologic diagnosis also is unreliable in many cases, as the histologic patterns of idiopathic FM and LAFM overlap. In this article, we discuss the importance of close clinical follow-up in patients with patch-stage mycosis fungoides (MF) or FM who have had a nondiagnostic histopathologic evaluation. We also highlight the value of ancillary testing, including T-cell receptor gene rearrangement, flow cytometry, and immunohistochemistry, as a component in the diagnostic process rather than the sole diagnostic moiety. Diagnosis and classification of idiopathic FM and LAFM continue to pose challenges for dermatologists, oncologists, and pathologists, and no single diagnostic tool is sufficient in providing diagnostic certainty; rather, a collective evaluation of pathologic, molecular, and clinical criteria is required. Currently, classification of idiopathic FM and LAFM incorporates clinical information and histologic assessment, but little consideration is given to the implications of the diagnosis from the patient's perspective. Revisiting histologic classification of these entities while incorporating the patient's perspective may prove beneficial to dermatologists as well as patients.

Diagnostic error assessment and associated harm of endoscopic ultrasound-guided fine-needle aspiration of neuroendocrine neoplasms of the pancreas.

BACKGROUND: Over the past decade, the standardization of error classification in anatomic pathology has become an important issue. The objective of the current study was to assess the extent of errors occurring in the cytopathologic diagnosis of neuroendocrine lesions of the pancreas, and to classify these errors and their associated harm. METHODS: Information on all cases diagnosed as a neuroendocrine neoplasm either by endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) in cytology or by surgical pathology between 2000 and 2012 was collected. Using standardized error and harm classification, the authors reviewed the cytology and surgical pathology material and evaluated the type and the cause of diagnostic errors and their impact on the patient. RESULTS: A total of 177 patients who underwent EUS-FNA were diagnosed with a neuroendocrine neoplasm either by cytology or surgical pathology. Eighty of these cases had surgical follow-up available at the study institution. Of these 80 cases, 56 had an adequate cell block and immunohistochemistry was performed. There were 14 discrepancies noted between cytologic and surgical pathologic diagnoses. There were 9 false-negative cases, consisting of 3 interpretation errors and 6 cytology sampling errors. There were 5 misclassifications, including 4 cases of solid pseudopapillary neoplasm and 1 case of neuroendocrine carcinoma (diagnosed as adenocarcinoma on cytology). There were no surgical pathology errors noted. All errors were associated with no or minor harm. CONCLUSIONS: EUS-FNA of pancreatic neuroendocrine neoplasms has excellent diagnostic performance, with no false-positive diagnoses reported. When an adequate sample is obtained, the most significant error is misclassification, which is most often associated with solid pseudopapillary neoplasm. The harm associated with diagnostic errors is at most minor.