Ki-67 cytological index can distinguish well-differentiated from poorly differentiated pancreatic neuroendocrine tumors: A comparative cytohistological study of 53 cases

Gabriele Carlinfante, Paola Baccarini, Debora Berretti, Tiziana Cassetti, Maurizio Cavina, Rita Conigliaro, Alessandro De Pellegrin, Luca Di Tommaso, Carlo Fabbri, Adele Fornelli, Andrea Frasoldati, Giorgio Gardini, Luisa Losi, Livia Maccio, Raffaele Manta, Nico Pagano, Romano Sassatelli, Silvia Serra, Lorenzo Camellini

Research output: Contribution to journalArticlepeer-review

Abstract

The Ki-67 labeling index has been found to bear prognostic significance in gastrointestinal neuroendocrine tumors (NETs), and it was recently incorporated in NET histological grading. Nevertheless, a reliable preoperative determination of NET grading could be useful in clinical practice. The aim of this study is to compare the results of Ki-67 labeling index, as measured on cytological samples and on surgical specimens of patients with pancreatic NETs (P-NETs). We also investigated whether concordance might be improved, using a 5 % (instead of 2 %) cutoff value for defining G2 tumors. We retrospectively identified 48 consecutive patients with 53 P-NETs, from our five institutions, and we measured Ki-67 labeling index on their cytological samples and surgical specimens. The traditional 2 % and the alternative 5 % cutoff values were used to classify G2 tumors. The concordance rate between cytological and histological grading was 46/53 (86.8 %; weighted κ statistic 0.77; 95 % confidence interval (95 % CI) 0.60-0.94). No cases of cytological G1-G2 NETs were upgraded to G3 neuroendocrine carcinoma (NEC) at histological grading. Cytology was found to be highly specific in the diagnosis of both G2 (94.1 %; 95 % CI 80.3-99.3) and G3 tumors (100.0 %; 95 % CI 92.8-100), but the sensitivity was poor for G2 NETs (66.7 %; 95 % CI 38.4-88.2) and high for the prediction of G3 NECs (100 %; 95 % CI 39.8-100.0). When the 5 % cutoff value was adopted, concordance rate was 49/53 (92.4 %; weighted κ 0.82; 95 % CI 0.64-1.00). In conclusion, Ki-67 cytological expression can distinguish well-differentiated (both G1 and G2) from poorly differentiated P-NETs, and it may be useful for their preoperative classification.

Original languageEnglish
Pages (from-to)49-55
Number of pages7
JournalVirchows Archiv
Volume465
Issue number1
DOIs
Publication statusPublished - 2014

Keywords

  • Cytological grading
  • Endoscopic ultrasound-guided fine needle aspiration
  • Ki-67
  • Pancreatic neuroendocrine tumors

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Cell Biology
  • Molecular Biology

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